Sage 50: "You cannot change the number or currency of an account
Sage 50 blocks edits to an account's number or currency once any transaction has touched the account; here is why, and what you can do about it.
“You cannot change the number or currency of an account once it has been used.” That is Sage 50 refusing an edit, not reporting that anything is wrong with your file. The account you tried to change already has history attached: at least one transaction, journal entry, or other reference points at it, so its number and its currency are now frozen. Nothing is corrupted and the account keeps working; you simply cannot change those two properties through the edit screen.
Why the number and currency are locked
The account number is how Sage 50 identifies the account everywhere in the ledger, and the currency decides how the account’s balances are stored and valued. If either could be edited after postings existed, every historical transaction would silently point at a different account, or carry amounts in a currency it was never balanced in. Rather than rewrite your history, Sage 50 blocks the change. Note that “used” can mean less than you expect: a single old journal entry, a budget, or a posting in a closed fiscal year is enough, so an account you think of as unused may still be locked.
Keep the number, change what you can
The lock applies to the number and the currency, not to everything on the account. You can generally still edit the account’s description so your chart of accounts reads the way you want. If your goal was clarity rather than a new numbering scheme, renaming the account is the safest fix and touches nothing underneath it.
Create the account you wanted, then retire the old one
If you genuinely need a different number or a different currency, add a new account with those settings and use it going forward. History stays on the old account, which keeps your records intact. Once nothing new needs to post to it, you can usually mark the old account inactive so it drops out of day-to-day lists while its balances remain available for reporting. This is the standard, audit-friendly way around the message.
Check what “used” actually means
Before restructuring anything, look at what is referencing the account. Budgets, recurring templates, or linked defaults can make an account count as used even when its transaction history is thin, and removing an unwanted reference sometimes unlocks the edit. Do not delete real transactions to force the account open; that damages your audit trail and rarely produces the result people hope for.
When the change has to happen in the data
Some situations cannot be solved from the edit screen at all: a currency that was set wrong years ago and now carries years of postings, or a full renumbering of the chart of accounts under a new scheme. Changes like those are applied to the data itself rather than through the window, which is work our engineers do regularly. If the whole company needs a different functional currency, that effectively means rebuilding into a new company file and migrating everything across, which is a conversion project we can scope from your file. You can request a free evaluation of your specific file with no obligation.
If you are converting to QuickBooks anyway
If this message appeared while tidying up before a move to QuickBooks, you can stop tidying. Account numbers and currencies are remapped during conversion, so an awkward numbering scheme in Sage 50 does not need to be fixed there first; our Sage 50 to QuickBooks conversion service handles the mapping for you.
Start by deciding whether a rename or a replacement account solves the problem. If it does not, write down exactly which accounts need to change and what the target number or currency is; that short list is the most useful thing you can hand anyone who ends up working on the file.