You cannot change your Billing Method from Percent of Proposal" Sage 50 message
Sage 50 is blocking a job's billing method change because open proposals are still linked to that job, and they must be dealt with first.
The message
You cannot change your Billing Method from Percent of Proposal or No Progress Billing when you have open Proposals applied to the job.
is Sage 50’s way of saying: this job still has proposals that have not been closed out, and those proposals are tied to the job’s progress billing setup. Because the billing method controls how those proposals generate invoices, Sage 50 refuses to change it while the link is live. It is a data-integrity guard, not a corruption warning, and in most cases it can be resolved without outside help.
Why it happens
Progress billing on a job is driven by its billing method, such as “Percent of Proposal.” When a proposal is applied to a job and remains open, Sage 50 expects to keep calculating invoices from it under the current method. Changing the method mid-stream would leave those proposals calculating against rules that no longer exist, so the program locks the setting until every open proposal applied to the job is resolved.
Close or delete the open proposals
The safest first step is to review the proposals applied to the job and close out the ones that are finished. A proposal that has been fully invoiced, or that you know will never be invoiced, can typically be closed so it no longer counts as open. Proposals that were created in error can be deleted if your workflow allows it. Once no open proposals remain applied to the job, the billing method field should become editable again. The exact screens and options depend on your Sage 50 edition and version, so work from the proposals list for that job rather than guessing at menu locations.
Check for proposals you forgot about
A common surprise is an old proposal from a prior year that was never closed and is still quietly attached to the job. Filter the job’s proposals by status rather than date so stale entries surface. Closing one forgotten proposal is often all that stands between you and the setting you want.
Consider whether you truly need the change
If the job is nearing completion and only an invoice or two remains, it may be simpler to finish billing under the current method and apply the new billing method to the next job you set up. That avoids disturbing history that has already been invoiced, which is generally the cleaner accounting outcome.
If the proposals will not close, or the setting stays locked
Occasionally a proposal refuses to close or delete, or the billing method remains locked even after every proposal appears resolved. That usually points to damaged links between the proposals, the job, and the billing records, and forcing it by hand can make things worse. This is the situation where the file needs professional attention: our engineers repair damaged Sage 50 / Simply Accounting databases and can untangle broken job and proposal links directly in the data. We offer a free evaluation of damaged Sage 50 databases so you know what is wrong before committing to anything.
If you were changing billing methods as part of a move to QuickBooks
If the real goal is getting this data into QuickBooks and Sage 50’s progress billing rules are in the way, that is a conversion question rather than a repair question. Our Sage 50 to QuickBooks conversion service handles jobs, estimates, and invoicing history, and a free quote will tell you what carries over.
Next step: pull up the proposals list for the affected job, close or delete everything still open, then retry the billing method change. If the lock persists, send us the file for a free evaluation rather than experimenting further.