VAT return review checklist before submission

Reconciliation

Reconcile the bank accounts to the period end
Agree the VAT control account to the return and to the previous return's payment or repayment
Check sales and purchase invoices are dated in the right period
Check the records are kept digitally and data moves between software by digital links, since copy and paste is not a digital link (HMRC: VAT Notice 700/22)

Check whether construction services bought or sold fall under the domestic reverse charge: both parties VAT-registered and the payments reported under the Construction Industry Scheme (GOV.UK: when you must use the reverse charge)
As supplier, enter only the net value of reverse charge sales and no output tax (HMRC: reverse charge technical guide)
As customer, add the VAT to output tax and reclaim it as input tax under the normal rules, with the purchase kept out of net sales (HMRC: reverse charge technical guide)
Keep any written notice that the customer is an end user or intermediary, which takes the supply outside the reverse charge (GOV.UK: if you buy construction services)

Download the monthly postponed import VAT statements, which can only be accessed for 6 months from publication (GOV.UK: get your postponed import VAT statement)
Include postponed import VAT in box 1 and the amount reclaimed in box 4, with the value of the imports in box 7 (GOV.UK: complete your VAT return for import VAT)

For a client with exempt supplies, check whether exempt input tax is within de minimis: £625 a month on average and no more than half of all input tax (HMRC: VAT Notice 706)
Apply the simplified tests where they fit (HMRC: VAT Notice 706)
Make the annual adjustment on the first return after the end of the longer period, or bring it forward to the last return of that period (HMRC: VAT Notice 706)

Correct net errors of up to £10,000 on the current return (HMRC: VAT Notice 700/45)
Correct net errors between £10,000 and £50,000 on the return only where they are no more than 1% of box 6
Notify HMRC separately of errors over £50,000, errors over 1% of box 6, and any deliberate error (HMRC: VAT Notice 700/45)
Check the error falls within the 4-year time limit from the end of the period in which it happened

Have the client approve the return
Submit and pay by 1 calendar month and 7 days after the period end (GOV.UK: VAT return deadlines)
Keep HMRC's receipt with the return