Tax-systems fluency in at least one domain (indirect tax engines, corporate tax provision or compliance tooling, withholding, research credit, or transfer pricing systems), gained at a tax-technology practice, a tax software vendor, or an in-house tax-systems team. Build and iterate tax-specific products and internal tooling across the full tax stack, including indirect tax reconciliations, provision and research credit data pipelines, transfer pricing datasets, withholding tracking, and exemption and validation tooling.