erp-brick-tax

The tax brick (module tax, spec v2, UK VAT first): the right VAT on every quote, order and invoice without anyone choosing a rate. A product carries a tax category, a customer a treatment; a dated rule turns the pair into a tax code, and the code's rate on the tax point is charged — rounded the way HMRC allows and frozen on the invoice at issue.

See AGENTS.md for where a change goes and the rules that must not be undone. Built from erp-method modules/tax/module.yaml (signed 2026-10-22).