When I try to put an expense (purchases) in, the vat 20% is wrong, and when I save the amount I list changes to a different amount and it is the same with sales.

Hello @userstephenmcgeough7,

Let's perform a few browser troubleshooting steps so you can create sales and purchases with the correct calculated VAT.

To start with, let's consider logging in to your QuickBooks Online account using a private or incognito browser so we can isolate this issue. To do so:

• Google Chrome: Ctrl + Shift + N
• Mozilla Firefox: Ctrl + Shift + P
• Safari: Command + Option + P

If this works, you can clear your regular browser's cache so the system can start fresh. But if you get the same results while using a private browser, use a different browser app instead.

Additionally, I've also included this reference for a compilation of articles you can use while working with us: Making Tax Digital with QuickBooks Online.

If there's anything else that I can help you with, please let me know by leaving any comments below. I'll be here to lend a hand.