An invoice integration adds tax twice: agree whether each amount is net or gross

Put a basis beside the amount

For each invented line, name currency, quantity, unit amount, whether the unit amount includes tax, the approved tax treatment and any permitted discount. A field labelled amount is insufficient. Formatting it to two decimals does not tell the destination whether tax is included. The finance owner or their qualified adviser supplies the applicable treatment; this guide does not decide rates, exemptions or tax liability.

• Separate monetary basis from which account or tax identifier is mapped.
• Do not assume a blank tax field means exempt or zero-rated.
• The actual connector's supported fields must be verified; no Xero or QuickBooks action configuration is prescribed here.

A synthetic double-tax counterexample

Assume solely for invented arithmetic a net amount of 20.00 and a 20% rate. The declared result is 4.00 tax and 24.00 gross. If 24.00 is passed as a net amount and another 20% is added, the result becomes 28.80. The 4.80 difference is a basis mistake, not merely a penny-rounding issue. These numbers are not a recommendation to apply that rate to any real supply.

• Assert the net, tax and gross components, not only the grand total.
• If the approved basis is unknown, hold the proposed draft instead of trying both settings on real invoices.

Rounding and tax setup belong to an explicit policy

HMRC's UK guidance distinguishes invoice traders from retailers and describes different rounding treatments. It cannot safely be reduced to always round down or always round each line. Agree the policy that applies to the business, then record where rounding occurs and how the destination applies it. The related synthetic example exposes a line-versus-invoice difference without choosing a legally applicable policy.

• Do not adjust a final total merely to hide disagreeing component amounts.
• No live invoice, tax configuration or financial correction has been performed.

Mapping repair is not tax advice

Use the existing maintainer, vendor help or your finance adviser when the policy or account setup is unresolved. A missing field under an already approved treatment may be discussed through the existing £145 five-field Sheets-to-Xero mapping offer, only with its working trigger and authorised disposable-draft route. Fixing tax configuration, deciding tax policy, custom arithmetic, historical invoices and live sending are outside that offer. Send invented net/tax/gross expectations and the missing mapping, not tax returns, customer details or credentials. Scope must be confirmed; the price is untested and payment follows agreed checks and sign-off.