Sage sales tax best practices include putting a bunch of sales tax rates under a single ID and making changes to the rates as needed.

You may be wondering what happens to prior transactions when you update those rates:

Updating the rate does nothing by itself.  Opening an invoice in a prior period and closing it won't make any changes.  But opening an invoice and clicking into the sales tax box (even without making any change) DOES update the sales tax to the new rate which will change your sales tax payable and the amount due on an invoice whether it had been paid or not.  You will be asked to save the changes when you close the invoice and you may know to choose no, but if you work in a multiuser environment your sales people may not realize the importance of this since they aren't aware they changed anything.  If your prior year is open, it can be changed there also which will make your tax accountant hate you.  Since only 24 periods can be open at a time, it can't affect things >2 years old.

A solution that was proposed years ago was to allow a user to choose a starting date for changes to the rates for each tax ID.  This would fix our issue and provide a ledger of rate changes over time.  As that proposal is still under review, I don't assume this is a major concern for Sage.  You could close your periods monthly, but if your sales people need to email invoices to customers, they will be unable to do so (the email button will be greyed out and they'll get a note about not having access to invoices in closed periods).

If a change was made accidentally, I don't think there is an easy way to track down what invoices were changed if you didn't know when they were changed.  If you do many transactions in a month this would be a hellish undertaking.

Can I get someone else to confirm this is the case?