Open Settings > Tax Rates. This area requires Full Access and Manage Rates.
Tax Rates stores the rates used by invoice defaults. Enter rates approved by your organization's finance team; these fields configure calculations rather than determine tax obligations.
At least one component is required. Use Add Component, enter each component's name and Rate, and choose Compound where appropriate. Compound components calculate on top of prior rows, so component order matters. Review the displayed Effective values and combined result before saving.
Once a rate is used on invoices, its country and rate components are locked; metadata can still be updated. Create an appropriate new rate for a changed calculation instead of expecting old invoice calculations to be rewritten.