Full Stack Ruby on Rails Software Engineer (Senior - Remote) Brightline IncFull Stack Ruby on Rails Software Engineer (Senior - Remote)NYRemote$149,000–$175,000 / yearWe are seeking a Full Stack Ruby on Rails Senior Software Engineer to help us scale our core platform, build robust internal and external integrations, and evolve the data flows that power our clinical and billing infrastructure. Brightline is based in Palo Alto and is backed by investors including Boston Children's Hospital, Northwell Health, Blue Cross Blue Shield of Massachusetts, Google Ventures, KKR, and Oak HC/FT.
Assistant Site Manager RendrAssistant Site ManagerFlushing, NYWe strive to provide world-class, value-based health care with kindness at more than 100 clinical offices throughout Brooklyn, Manhattan, Queens, Staten Island, and Nassau County. Essential Functions : Assists with and may have respnsiblity for the hiring process, new employee integration, performance management, and employee development of the front office/desk and non-provider clinical team.
Experienced Medical Claims Biller II POM RecoveriesExperienced Medical Claims Biller IIFarmingdale, New YorkJoin our team as an Insurance Claims Follow-up Specialist, where you'll leverage your expertise in medical collections, denial processing, appeal submission, and EOB review to resolve unpaid claims effectively. Are you a seasoned professional with a minimum of 2 years of hospital in-patient and out-patient claims follow-up experience?
Billing Coordinator - Legal - NYC Page GroupBilling Coordinator - Legal - NYCNew York, NY$80,000–$105,000 / yearFull timeThis position partners closely with attorneys and administrative teams to maintain billing compliance, monitor unbilled inventory, and support efficient revenue collection processes. Responsible for managing the full billing cycle, ensuring timely and accurate invoice preparation, submission, and resolution of billing-related issues for a portfolio of legal matters.
Change Order Management Specialist Page GroupChange Order Management SpecialistAmityville, NY$95,000–$115,000 / yearFull timeThe Change Order Management Specialist is responsible for tracking, documenting, and supporting the preparation and submission of change orders on construction projects. Collect, organize, and maintain supporting documentation, including RFIs, field reports, drawings, schedules, directives, photos, quotes, invoices, and correspondence.
Coordinator, Billing Compliance Paul Hastings LLPCoordinator, Billing ComplianceNew York, NYIn this capacity, the Coordinator, Billing Compliance will: Ensure all bills firm-wide are processed accurately, timely, and in accordance with the Client Billing Guidelines and the Firm's internal procedures; Review and manage audit of all existing and new matters opened are in compliance with firm requirements using appropriate billing system matter codes; Coordinate with Conflicts, Terms, Pricing, eBilling, Time and Collections to ensure matters are opened to comply with Paul Hastings requirements; Support process improvements within Intapp Open and Intapp Time; Support projects as assigned to ensure matters are maintained to comply with client guidelines; Support projects to audit and improve OCG compliance; Secure communications with billing attorneys and CSS's regarding adherence to clients' requirements; Respond to all billing requests from billing attorneys, CSS's, clients, and other internal teams; Provide all billing reports requested; Team with Financial Services to ensure proper support for billing updates and upgrade projects; and. Proficiencies: Advanced proficiency in administering windows and web-based accounting programs, particularly for legal-specific accounting systems (Elite); Advanced proficiency in document management systems (WorkSite, FileSite, DeskSite, Equitrac); Advanced proficiency in MS Office Suite applications; Advanced proficiency in financial forecasting programs (targetCash); and.
Billing Coordinator II - Urology New York University School of MedicineBilling Coordinator II - UrologyMineola, NY$66,300–$72,345 / yearPreferred Qualifications: Certified Coding Specialist Certification (CCS) or Certified Coding Specialist- Physician-based (CCS-P) or Certified Professional Coder (CPC), Certified Outpatient Coding (COC) preferred. Collaborate with the corporate Revenue Integrity Analysts to understand CPT and ICD-10 guidelines, payer policy and procedure manuals, updates, and CMS publications to ensure practices are compliant with current policies and procedures.
Billing Coordinator II Opportunities - Long Island New York University School of MedicineBilling Coordinator II Opportunities - Long IslandLong Island, NYCollaborate with the corporate Revenue Integrity Analysts to understand CPT and ICD-10 guidelines, payer policy and procedure manuals, updates, and CMS publications to ensure practices are compliant with current policies and procedures. Detail oriented with high level of accuracy for reviewing charge batch submissions, analyzing and correcting coding denials, preparing, and presenting analyses.
Billing Coordinator- 3610190 AMS StaffingBilling Coordinator- 3610190New York City, New YorkCoordinate with Partners, Attorneys and Secretaries to manage time entries and edits, adjustments, write-downs, rate management and bill posting. As a Billing Coordinator, you are responsible for all aspects of drafting and finalizing client invoices for a group of dedicated attorneys.
Phlebotomist / Administrative Assistant (Park Slope) One MedicalPhlebotomist / Administrative Assistant (Park Slope)New York, NY$24–$26 / hourUse impeccable C-I-CARE (a framework containing the key elements of a great interaction and effective communication that we use with patients and each other) in all patient interactions, both clinical and administrative, and ensure a fluid and positive in-office experience through patient intake, same day schedule management, appropriate follow up scheduling, strong knowledge of billing and insurance, monitoring patient feedback and assisting with outreach as necessary. As a One Medical Phlebotomist/Administrative Assistant (internally known as Lab Services Specialist/Member Support Specialist) at one of our offices, you’ll provide an exceptional experience for our patients and help them accomplish an important part of their care journey by providing venipuncture as well as other clinical support services.
NewLegal Billing Coordinator CFSLegal Billing CoordinatorNew York, NY$90,000–$110,000 / yearBilling Coordinator Billing Coordinator Billing Coordinator Billing Coordinator Billing Coordinator Billing Coordinator. Gain hands‑on exposure to complex client billing and high‑value legal matters.
Senior Billing Coordinator- 3625751 AMS StaffingSenior Billing Coordinator- 3625751New York City, New YorkThis individual will work to develop relationships with assigned partners and secretaries and create individualized billing plans according to partner preference. Essential Duties and Responsibilities include the following: Proactively monitor unbilled index of each assigned billing partner to identify opportunities to issue bills.
NewBilling Specialist Allied UniversalBilling SpecialistNew York, NYThis position is responsible for providing support to the City of NY agencies in the Long Island City, NY office to compose and audit billing packages (both paper and electronic) which consist of invoices, certified payroll reports and sign-in sheets. Emphasis on quality control by ensuring that hours are accurate and balance, Prevailing Wage rates and Supplemental Benefit rates are accurate, and Bill Rates are accurate.
Billing Specialist SimilarwebBilling SpecialistNew York, NY$75,000–$95,000 / yearOur unique data and solutions empower over 6,000 customers globally, including industry giants like Google, eBay, and Adidas, to make game-changing decisions that drive their digital strategies. *All Similarweb offices work in a hybrid model, so you can enjoy the flexibility of working from home with the benefits of building face to face connections with fellow Similarwebbers.*.
New["Billing Supervisor","Billing Supervisor"] Ambulnz NY, LLC["Billing Supervisor","Billing Supervisor"]Ridgewood$25–$30 / hourWe pledge ourselves to crafting and maintaining an environment that respects diverse traditions, heritages, and experiences.
Billing Specialist Healthy PharmacyBilling SpecialistElmhurst, New York$18–$25In addition, this person will be expected to track Key Performance Indicators, create reporting and analytics, improve processes where needed and be responsible for maximizing the overall efficiency of the company’s accounts receivable collection efforts. This will involve sharing duties of calling for eligibility and authorizations, re-submissions of denied claims, negotiating with insurance carriers, and the follow-up of non-paid and underpaid claims.
Billing Specialist EvertuneBilling SpecialistNew York City, New YorkOur billing process is complex and highly manual today, including usage-based billing inputs, customer-specific pricing rules, contract interpretation, invoice revisions, customer portal uploads, PO requirements, payment application management, and collections follow-up. Bachelor’s degree in Accounting, Finance, Business, Economics, or a related field preferred; 0-3 years of experience in billing, AR, AP, collections, finance operations, accounting, operations, or another detail-oriented role also welcome.
Executive Director, Enterprise Billing Strategy, Bureau of Office of Chief Medical Officer City of New YorkExecutive Director, Enterprise Billing Strategy, Bureau of Office of Chief Medical OfficerQueens, NYA master's degree from an accredited college in hospital administration, public health, community health, health administration, emergency preparedness planning/management, emergency medical services, fire safety, law enforcement, homeland security, project management, public administration, business administration, management, or administration and three years of full-time satisfactory experience in a health services setting such as a laboratory, hospital, or other patient care facility, or in a public health, community health, environmental health, school health, social services, or mental hygiene program, of which at least 18 months of experience must have been in a managerial or administrative capacity requiring independent decision-making concerning program management, planning, evaluation for quality improvement and assurance, allocation of resources, and the scheduling and assignment of work; or. The Executive Director must bring a demonstrated, hands-on track record of personally standing up billing infrastructure for non-traditional provider types community health workers, doulas, peer specialists, and health educators in a Medicaid-dominant payer environment, from initial design through first revenue generation, with measurable financial results.
Billing Specialist Release RecoveryBilling SpecialistNew York, NY$65,000–$75,000 / yearThis individual will work closely with the Director of Business Operations and Director of Revenue Operations to ensure that cash pay invoicing, contracting, and insurance claims are accurate, timely, and reimbursed in full. Manage extension requests and contracts, including communication with clients and guarantors regarding billing questions and account needs.
Billing Specialist East Coast Warehouse & Distribution CorpBilling SpecialistElizabeth, New JerseyYour duties will include verifying all details pertaining to warehouse, TL and LTL orders, and communicating with customers to obtain approval of additional charges, changes, etc. Check daily and weekly FSC charts for accurate customer charges.
Billing Analyst DO & CO AGBilling AnalystJamaica, NY$65,000–$75,000 / yearDiversity & Inclusion Statement: We want everyone to feel welcome, respected and we are committed to providing the best space, experience, and workplace for our teams - no matter what race, color, religion, sex, sexual orientation, gender identity, national origin, veteran, or disability status and all the other fascinating characteristics that make us different and make you. With the three business segments of Airline Catering, International Event Catering, and Restaurants, Lounges & Hotels, DO & CO offers gourmet entertainment all over the world.
Revenue Integrity Analyst (FGP) - Manhattan, CBO North Billing (CPC highly preferred) New York University School of MedicineRevenue Integrity Analyst (FGP) - Manhattan, CBO North Billing (CPC highly preferred)New York, NY$70,481.60–$94,605 / yearKnowledge of: Current Procedures Codes (CPT) and International Class of Diseases Codes (ICD9/10) utilized in medical billing; Medical billing software; Healthcare billing including Medicare, Medicaid, or other third-party payers; Terminology utilized in medical billing; English usage, grammar, and spelling; Basic math. Conducts special projects and special studies to facilitate revenue management as required for system conversions, new facilities/acquisitions, new departments, new service lines, changes in regulations, legal reviews, etc.
Customer Billing Specialist Unit 4 NVCustomer Billing SpecialistNY$20,724–$21,874 / yearWhat we offera culture built on trust and accountability - giving you the freedom and autonomy to be successful and make an impactbalance - with our Flexible Leave Paid Time Off policy, remote working opportunities, Global Wellbeing Days, and other great benefitsgrowth opportunities - we provide the tools and guidance required so that you can focus on what really matters to you and so, ultimately, you can achieve your best worktalented colleagues, role models and mentors - work, learn and be inspired by some of the best talent in the software industrya commitment to sustainability - with initiatives such as our Environmental, Social, and Governance strategy and Act4Good programmea safe and inclusive working environment - supported by our Employee Resource Groups, which are open to all. Other jobs at Unit4 See all jobs Customer Billing SpecialistLisbon, PortugalRead more Product OwnerWrocaw, PolandRead more Product Director, Innovation & New Ventures London, United KingdomRead more.
Assistant Director of Patient Billing, Bureau of Revenue City of New YorkAssistant Director of Patient Billing, Bureau of RevenueQueens, NYA baccalaureate degree from an accredited college or university, accredited by regional, national, professional or specialized agencies recognized as accrediting bodies by the U.S. Secretary of Education and by the Council for Higher Education Accreditation (CHEA), including or supplemented by 24 semester credits in accounting, including one course each in advanced accounting and auditing; or. As the primary population health strategist and policy authority for NYC, with a rich history of public health initiatives and scientific advancements, from addressing the 1822 yellow fever outbreak to the COVID-19 pandemic, we serve as a global leader in public health innovation and expertise.
Billing and Coding Assistant Columbia UniversityBilling and Coding AssistantNew York, NY$68,000–$73,000 / yearReporting to the Coding Manager, this role is responsible for independently reviewing complex clinical documentation, interpreting coding and payer regulations, and ensuring accurate and compliant charge capture across multiple service lines. Independently review and interpret clinical documentation to ensure accurate, compliant, and complete charge capture across pain medicine and related specialties.
Manager, Billing and Follow-up BetterHelpManager, Billing and Follow-upNY$120,000–$150,000 / year5-7 years of experience in the healthcare space, preferably in an existing role doing end-to-end billing and follow-up functions with insurance companies on behalf of providers. We ask employees to travel to our San Jose, CA office up to three times per year plus one company-wide offsite to collaborate in person and strengthen working relationships.
NewBilling Coordinator CFSBilling CoordinatorNew York, NY$90,000–$115,000 / yearBilling Coordinator Billing Coordinator Billing Coordinator Billing Coordinator Billing Coordinator Billing Coordinator. Gain hands‑on exposure to complex client billing and high‑value legal matters.
e-Billing Rate Compliance Administrator Wilson Elsere-Billing Rate Compliance AdministratorWhite Plains, New YorkA variety of factors are considered in making compensation decisions, including but not limited to experience, education, licensure and/or certifications, geographic location, market demands, other business and organizational needs, and other factors permitted by law. Wilson Elser welcomes submissions of candidates for our open positions exclusively from recruitment agencies with an active, signed fee agreement who have been granted access to a position through our dedicated Recruitment Agency Portal.
Insurance Eligibility and Medical Billing Assistant Ohel Children's Home and Family ServicesInsurance Eligibility and Medical Billing AssistantBrooklyn, New York$50,000–$55,000 / yearIn this role, you will play a key part in supporting the revenue cycle by verifying insurance eligibility, minimizing claim denials, facilitating timely reimbursements, and helping maintain the financial integrity of our programs through accurate documentation and effective collaboration with billing staff. Build and maintain positive working relationships with clients, payers, and internal departments to resolve claim denials, reimbursement issues, and payer discrepancies.
Senior Principal Business Solutions (Pre-Sales) - Insurance Billing MajescoSenior Principal Business Solutions (Pre-Sales) - Insurance BillingNY$125,000–$155,000 / yearAs leaders in intelligent SaaS solutions, we've embedded AI and Agentic AI throughout our robust product portfolio of core, underwriting, loss control, distribution, digital solutions, and pension & retirement administration so our customer can reimagine their business with real-time business insights, optimized operations, and enhanced business outcomes. This is a high-impact, customer-facing position for someone who can partner with sales teams, lead functional discovery discussions, shape modernization conversations, and demonstrate how billing and accounts receivable solutions solve real business problems for P&C insurers across North America.
Billing & Accounts Receivable Specialist Release RecoveryBilling & Accounts Receivable SpecialistRye, NY$65,000–$75,000 / yearThis individual will work closely with the Director of Business Operations and Director of Revenue Operations to ensure that cash pay invoicing, contracting, and insurance claims are accurate, timely, and reimbursed in full. Manage extension requests and contracts, including communication with clients and guarantors regarding billing questions and account needs.
Clinical Research Finance Analyst - Clinical Trial Billing New York University School of MedicineClinical Research Finance Analyst - Clinical Trial BillingNew York, NY$70,481.60–$75,000 / yearThis position liaises with internal and external customers, consults with faculty, the Clinical Research Support Unit, and Departmental Administrative personnel regarding billing, accounts receivable, payment reconciliation and accurate and timely completion study closure process. This position provides post-award financial management of industry sponsored clinical trials, ensuring accurate and timely payments from clinical trial sponsors.
Associate Director of Billing & Coding ONS MSO LLCAssociate Director of Billing & CodingStamford, CTThe Associate Director actively reviews coding trends, resolves escalations, conducts audits, provides education and partners with clinical and operational leaders to reduce denials, prevent revenue leakage, and strengthen documentation practices. Headquartered in Stamford, Connecticut, the Spire network spans the Northeast with more than 165 physicians, 1,800 employees, 285 other clinical providers and 40 locations in New York, Connecticut, Rhode Island and Massachusetts.
Senior Software Engineer (Agentic Search) - Billing NebiusSenior Software Engineer (Agentic Search) - BillingNew York City, New YorkWe are building a full-stack AI cloud platform that supports developers and enterprises from data and model training through to production deployment, without the cost and complexity of building large in-house AI/ML infrastructure. You will own the systems that turn product usage into accurate, trustworthy revenue, supporting flexible billing models—usage-based pricing, subscriptions, prepaid balances with auto top-up, and enterprise contracts.
NewPatient Registrar AxelonPatient RegistrarNew York, NY$20–$25 / hourRequests patients charts from Health Information and or physicians files and requests various patients NYPH medical record prior to appointment. Interfaces with MEU and Social Services to determine Medicaid eligibility; informs patients of documents required initiating Medicaid applications.
Product Owner - P&C Insurance Billing MajescoProduct Owner - P&C Insurance BillingNY$110,000–$170,000 / yearAs leaders in intelligent SaaS solutions, we've embedded AI and Agentic AI throughout our robust product portfolio of core, underwriting, loss control, distribution, digital solutions, and pension & retirement administration so our customer can reimagine their business with real-time business insights, optimized operations, and enhanced business outcomes. You'll collaborate with experienced leaders and global teams building and scaling AI-native solutions that solve complex, real-world challenges - where innovation moves from concept to production, decisions carry real weight, and execution matters.
Senior Software Engineer Agentic Search - Billing Nebius Group NVSenior Software Engineer Agentic Search - BillingNew York City, NY$147,200–$224,300 / yearWe are building a full-stack AI cloud platform that supports developers and enterprises from data and model training through to production deployment, without the cost and complexity of building large in-house AI/ML infrastructure. You will own the systems that turn product usage into accurate, trustworthy revenue, supporting flexible billing models-usage-based pricing, subscriptions, prepaid balances with auto top-up, and enterprise contracts.
Manager, Real Estate Billing-Hybrid Schedule Columbia UniversityManager, Real Estate Billing-Hybrid ScheduleNY$95,000–$105,000 / yearReporting to Associate Director, Student Financial Services, the Manager of Real Estate Billing serves as the subject matter expert for all real estate billing and owns the operational execution, controls, compliance, reporting, and continuous improvement of real estate billing across a complex residential and commercial tenant portfolio including approximately 2,000 residential and 120 commercial tenants with annual billing volume of approximately $3.8 million and $2 million respectively. The role reviews and approves complex transactions and account resolutions, serves as the escalation point for non-routine billing issues, develops procedures and metrics, coordinates collections escalation and audit responses, and supervises one direct report.
NewMedical Analyst – (Professional Coding) - Central Billing Office NYPMedical Analyst – (Professional Coding) - Central Billing OfficeNew York, NY$47.50–$53.35 / hourUtilize your outstanding analytical skills and keen attention to detail to take on this important role, responsible for performing varied and complex diagnostic and procedural coding for patient records and optimizing of DRG assignment. And as we look to the promising future ahead, we seek talented professionals like you to help drive our financial growth while building on our reputation for excellence as one of the nation’s top-ranked hospitals.
Sr Business Systems Analyst - Oracle Billing & Accounts Receivable Akamai Technologies IncSr Business Systems Analyst - Oracle Billing & Accounts ReceivableNY$88,900–$160,100 / yearAkamai's success relies on great customer service and customization throughout the post-purchase lifecyclecontracting, integration, billing, and receivablesdelivered efficiently through a diverse array of enterprise applications. For US based candidates only - the base salary for this position ranges from $88,900 - $160,100/year; a candidate's salary is determined by various factors including, but not limited to, relevant work experience, skills, certifications and location.
Senior Compliance Specialist New York University School of MedicineSenior Compliance SpecialistNew York, NY$84,577.92–$142,767.54 / yearConducts risk assessments to define audit priorities by evaluating previous audit findings, management priorities, ICD, APC, and DRG utilization patterns, national normative data, CMS, and PEPPER initiatives, OIG work plans and advisories, and healthcare industry best practices. The Senior Compliance Specialist (Hospital Billing Auditor) will support the Manager of Hospital Billing Compliance and the Director of Billing Compliance in the development and implementation of the Hospital Billing Compliance program at NYU Langone Health System to ensure adherence with federal and state billing regulations.
Operational Specialist New York University School of MedicineOperational SpecialistNew York, NY$61,288.35–$80,136 / yearThis role focuses on reviewing accounts, supporting resolution of complex billing issues, and assisting with implementation of workflow improvements identified through escalations and operational review. In this role, the successful candidate reporting to the Manager, Revenue Cycle Operations, the Operational Specialist supports hospital A/R process improvement efforts and escalation resolution through detailed analysis, workflow execution, and operational support.
NewHealth and Information Management/Patient Registrar AxelonHealth and Information Management/Patient RegistrarNew York, NY$18–$25 / hourPre-register patients in the hospital's online system and obtain hospital medical record numbers when necessary. Proficiency in telephone, computer, keyboard, effective communication, and customer service skills (Required).
Self-Pay & Financial Counseling Specialist II #Full Time 61st Street Service CorpSelf-Pay & Financial Counseling Specialist II #Full TimeNew York, NY$24.76–$33.17 / hourThe Self-Pay & Financial Counseling Specialist II is responsible for managing self-pay balances including installment accounts, receiving payments, and processing collection accounts. This role the individual is responsible for conducting financial assessments of patients in order to determine their ability to pay and reviewing patient registrations to ensure communication of patient out of pocket expense has occurred prior to visit.
Collection Specialist Maplewood Senior LivingCollection SpecialistWestport, CTBilling support: Serve as a knowledgeable, patient resource for general billing questions from residents, families, responsible parties, and internal staff-explaining charges, statements, and payment options clearly and compassionately. Long-term care insurance documentation: Prepare, submit, and track long-term care (LTC) insurance claims and supporting documentation, following up with carriers to ensure timely reimbursement and accurate account posting.
Coding Specialist III Columbia UniversityCoding Specialist IIINew York, NY$72,000–$85,000 / yearReview and follow up on denials related to coding and charge entry processes; if a claim is denied due to incorrect coding, conducts medical records research and corresponds with insurance companies and clinicians to resolve issue. The Coding Specialist III is responsible for the review and resolution of all coding related prebilling edits and/or rejections to ensure prompt and accurate reimbursement.
Epic Billing Analyst Your IT RecruiterEpic Billing AnalystJamaica, New YorkTechnical Expertise: Deep knowledge of Epic's Resolute Professional Billing or Hospital Billing modules, including charge router, work queue configuration, collection agency workflows, statement processing, and claims processing operations. Communication Skills: Excellent verbal and written communication skills to interact professionally with diverse stakeholders, including IT teams, clinicians, billing staff, and vendors.
Revenue Cycle Supervisor (Accounts Receivable) Columbia UniversityRevenue Cycle Supervisor (Accounts Receivable)Fort Lee, NJ$66,300–$78,000 / yearThe Revenue Cycle Supervisor (Accounts Receivable) is responsible for day-to-day supervision of a unit that is responsible for working and collecting on unpaid professional medical claims (government and all third-party payers). Ability to work collaboratively with a culturally diverse staff and patient/family population, strong customer service skills, demonstrating tact and sensitivity in stressful situations.
Analyst, Compliance Columbia UniversityAnalyst, ComplianceNew York, NY$80,000–$90,000 / yearProvide oversight and perform, as needed, ongoing, risk-based, and ad hoc coding auditing of complex services, across multiple specialties, rendered by physician and non-physician practitioners using current coding guidelines, with attention to Medicare/Medicaid, medical necessity, and NCD/LCD requirements; including but not limited to retrospective audits for established providers and prospective audits for newly onboarded providers to ensure appropriate documentation, coding accuracy, and billing compliance. Support departmental compliance teams by providing advisory guidance and expert knowledge of CPT/HCPCS and ICD-10 guidelines across multiple specialties, as well as teaching facility guidance, professional fee billing, including global surgical package rules, modifier usage, incident-to services, split/shared services, and emerging regulatory changes.
Director of Real Estate Allied UniversalDirector of Real EstateNY$130,000–$140,000 / yearDevelop and execute comprehensive corporate real estate strategies aligned with business growth objectives and operational requirements, implementing the company's strategic vision through management of real estate transactions. This includes Transaction Management (negotiating 100+ leases a year); Project/Move management (25+ moves/year); Lease Administration (database and rent payments) and Portfolio Management (acquisition synergies to estoppels).