How does “A period's three steps” work on the HMRC Dues page?

Each company × tax × period is one row on Returns, and its drawer walks it through Check, File and Pay. Check runs the pre-submission checks against Xero so the figures are right before anyone files. File records the filing made elsewhere — the date, the figures, and the return document itself, which Upload filed returns can also drop in bulk. Pay adds the filed liability to a payment run on the Payments tab, or records a payment made another way; once the period is settled the row reads Paid. Whether Xero agrees with a filed return is checked on the Reconcile tab only, where a difference is put right in Xero or explained. An old link to any of the earlier tab layouts still lands on the right place. Where: HMRC Dues (/accounts/hmrc-dues).