Thank you for bringing this to our attention, @LemonFresh.
We can perform some troubleshooting steps to sort out the error when adding Flat Rate Scheme (FRS) in QuickBooks Online (QBO). These issues can sometimes be caused by the browser’s overtime collection of data from frequent page visits.
Here are the keyboard shortcuts to open a private browser:
- Google Chrome: press Ctrl + Shift + N
- Mozilla Firefox: press Ctrl + Shift + P
- Microsoft Edge: press Ctrl + Shift + P
- Safari: press Command + Shift +N
If it works, kindly proceed with clearing your cache. This helps improve the performance of the application. Then, if the issue persists, you can refer to this article for other supported browsers while using QBO.
For further reference about editing FRS, you can check out this article: Flat Rate Scheme (FRS) in QuickBooks Online
Keep me posted in case you have other FRS or VAT concerns and questions. Have a good one!