Returns

CIS monthly returns (CIS300; contractor module only), one per tax month (the 6th to the 5th), identified by the calendar year and month the tax month ends in. An Open return collects the subcontractor invoices paid in its month; its totals, invoice and subcontractor counts and a per-subcontractor breakdown follow the payments. The submission child sends it to HMRC (POST), which is polled in the background until HMRC accepts it or reports errors (translated onto the return), and re-opens an accepted return (DELETE). Webhooks: return.submitted, return.accepted, return.failed, return.opened.