Hi there, PeachBomb.
Thank you for visiting the QuickBooks Community. I'll be sharing details on how VAT codes work in QuickBooks Online, then I'll ensure you'll be pointed to the right person to assist you further on this VAT matter.
Knowing which VAT codes to apply to each product and service will help you pay the right amount of tax and avoid any penalties when filing your VAT returns to HMRC. Then, the standard VAT rate in the UK for most goods and services is currently 20%. VAT-registered businesses must charge VAT at the standard rate on all goods and services unless they fall under another category. To see what vat code you should utilize and view extra details, you can open this artilcle: VAT codes in QuickBooks Online: A complete guide.
If you're still unsure and to ensure you're using the correct VAT code when setting up the onesaas intuit app to integrate your Amazon sales, I suggest consulting an accountant or contacting HMRC. They'll be able to provide you with suggestions on how to properly handle your sales, especially with the accurate VAT code to use for the entries.
Lastly, you may refer to this artilcle to view info on how you update VAT settings or edit VAT rates in QBO: Set up and edit VAT settings, codes and rates.
Please share with us and place a comment if you have additional questions about VAT codes. I'm always around to help, PeachBomb. Have a good one!