Hello there, grindforce.
The returns that we can only submit to HMRC are for the current fiscal year. That's why you get the message that the dates aren't compatible.
You'll want to reach out to HMRC again and ask how you can submit the return. To record it in QuickBooks, you can Mark it as Filed instead of the Submit to HMRC option.
- On the Sales Tax page, click Prepare return.
- Confirm the period and the details.
- Click the drop-down arrow beside Submit to HMRC and select Mark as Filed.
Let me know if you need anything else.