Mixed-rate baskets

A basket with a standard-rated product and a zero-rated one has to post as two lines with two tax codes, not one blended figure. If the integration collapses the basket to a single total, the VAT return is wrong from the first order and the error compounds.

Gift cards are not income

Selling a gift card is a liability, not a sale; redeeming it is the sale. Posting the card purchase as revenue double-counts income and misstates VAT. The integration needs to recognise the card SKU and route it to a liability nominal.

Marketplace and payment fees

Amazon and Stripe deduct fees before they pay you. If the integration posts the gross order and ignores the fee, the bank never reconciles. Fees belong on their own nominal line, taken from the settlement report rather than guessed.

Refunds and partial refunds

A refund is not a negative order — it may return part of a basket, keep a restocking fee, or refund shipping only. The integration has to map the refund lines explicitly and post a credit note that nets correctly against the original invoice.