As of API version 2026-01, tax calculation requests for tax partner apps now include buyer metafields. These fields provide custom data associated with customers (for D2C orders) and companies (for B2B orders) that may affect tax calculations. This enhancement allows tax partners to access merchant-defined buyer attributes for more accurate tax determination and compliance reporting.
This is a companion discussion topic for the original entry at https://shopify.dev/changelog/tax-summary-webhook-and-calculation-requests-now-include-customer-and-company-metafields