Can I change the Period Type and Tax Basis after I submit my first Quarterly Update?
You can change the Period Type only before submitting the first Quarterly Update for a tax year. HMRC locks it after the first submission. You can change the Tax Basis until you submit the last Quarterly Update. HMRC locks it after the last submission.
Before submitting an update, verify these values in the Send Quarterly Update to HMRC pop-up. If they’re correct, click Send Update. If the Period Type is incorrect, click Cancel before submitting the first update. Delete any existing quarterly updates, then fetch the obligations again with the correct Period Type and Tax Basis. Verify the values before submitting.