Made mistake importing bank statement. Money in was money out and vice versa. VAT return submitted.

Hello and welcome to the Community, DiverBloke

If the VAT return was successfully accepted by HMRC, it won't be possible to unfile. Instead, changes and corrections should be reflected on the next submission (rather than modifying the previously filed return). If your return was rejected or marked as filed, see how to unfile a VAT return in QuickBooks Online.

To correct an accepted VAT return, begin by deleting all transactions that were imported and reported incorrectly. This will create a VAT exception on your open VAT return for each transaction that was filed erroneously. 

Please note, it's not possible to batch-delete transactions or undo an import. The best way to delete is to go to the account that the transactions were posted against (from the Gear > Chart of accounts > Account history). Then, click onto the transaction to expand and select Delete. 

Next, import the transactions in the correct format and apply the correct VAT code. These will post to your open return as usual. 

As an alternative, you can adjust the amounts on your open VAT return (instead of deleting the transactions that were imported incorrectly).

1. Go to Taxes and select VAT.
2. Find the return you need to change and select Adjust to increase or decrease the amount as necessary.

We recommend speaking to your accountant or an accounting professional before creating an adjustment to make sure that your reports are correct after the adjustment. They can view these adjustments in the chart of accounts by searching for the accounts you've made adjustments to. 

If you don't already have an accountant, you can find a QuickBooks certified accountant near you on our online directory. Hope this helps!