Hi there,

Thank you for posting here in the Community space. I can share information about changing the VAT return's start date in QuickBooks Online.

The Start date is the end date of your previous return. Once filed, the only way to create or edit the previous return is by contacting our QuickBooks Support Team. 

Here's how you can contact support:

1. Click the Help option in the upper-right corner.
2. Go to the Search tab.
3. Click Contact Us.
4. Enter your concern, then select Continue.
5. Choose Chat.

Also, you can pull up VAT reports to view detailed information about your returns. You'll want to pull up the VAT Summary Report, VAT Detail Report, or VAT liability report.

Let us know if you still have more questions about managing VAT returns. We'll be sure to get back to you. Take care, and have a great rest of the day.