Can I correct an MTD quarterly update already submitted to HMRC? If I edit transactions now, will it update the old report or the next one?

We're unable to amend a submitted quarterly update directly. Instead, we can correct the bookkeeping for your mileage expense in QuickBooks Sole Trader.

Once completed, your corrected figures will automatically flow through and be included in your next quarterly MTD submission. Then, it will be captured by HMRC at your year-end finalisation as the point where you review, reconcile, and correct your full year's figures before they officially become your tax return.

Additionally, I recommend seeking professional advice to ensure that your financial records remain accurate: Find an accountant or bookkeeper near you.

Please let me know if you have any other concerns.