"Start over" is a feeling. It is not yet a scope.
When the books are wrong, the tempting sentence is "forget it, we'll start fresh." Sometimes that is the right call. Often it throws away a file that mostly ties, and then you pay to recreate history you already had.
The other temptation is to keep patching. A few journal entries, a few deleted duplicates, and the balance sheet looks calmer. If the cash still does not match the bank, you did not fix the books. You hid them.
A cleanup is the job when the file is the right file and it needs to be brought current and correct. Starting over, in the sense that matters, is a rebuild from the statements when the old file cannot be trusted. Catch-up versus monthly bookkeeping is the product split. This post is the cleanup-versus-rebuild split inside a file that is already behind.
When the old books are worth fixing
The old books are worth fixing when most months already tie to the bank, and the damage is a stretch you can name. A quarter where the card was not recorded. A loan that was posted to income. An owner payment sitting in a miscellaneous expense. That is cleanup. You keep the history that is right, and you correct the part that is not.
They are also worth fixing when your preparer, your lender, or a buyer needs the prior year to agree with what was already filed or already shown. Throwing the file away does not erase a return that was filed on it. It creates two stories. Cleanup keeps one story and repairs it.
You should see that conclusion in writing before you pay for the repair. The diagnostic is $499. It is read-only. It lists findings with dollar amounts and a fixed quote to fix them. The $499 credits toward the work if you approve it. If the findings say the file is sound enough to clean, you are not guessing.
When starting over is the honest scope
Start over, meaning rebuild from the statements, when the cash balance has been wrong for so long that you cannot tell which month broke. When prior "cleanups" were estimates. When the file will not open, or nobody will stand behind the opening balances. When the only source you trust is the bank.
In that case, keeping the old categories as a starting point usually imports the error. Reconstructing books from bank statements is the standard: the statement is the source, and memory is not. A licensed CPA still reviews the result before it goes out.
Starting over does not mean you lose the right to know the price. You still get the diagnostic first, then a fixed quote for the rebuild. You approve it in writing. You do not discover the scope after the invoice.
What not to decide from frustration
Do not decide because you are tired of the file. Tired is not a finding. A finding is "these three months do not tie" or "the opening cash has no support."
Do not decide because someone quoted a round number without reading the statements. A cleanup quote and a rebuild quote are different jobs. If they are the same price by coincidence, you should still know which one you bought.
Do not decide to keep a file just because it has years of history in it. History that does not tie is not an asset. It is a story you will have to unwind later, usually when someone else is asking.
How you actually choose
Send the statements and the file you have, even if you distrust it. Read the diagnostic. If the findings say a defined stretch is wrong, that is a cleanup, and book cleanups are the offer. If the findings say the balances cannot be relied on, the quote in front of you is a rebuild, and you should treat it as one.
Either way, a licensed CPA reviews the package before you hand it to a preparer, a lender, or a buyer. You are not asked to become the bookkeeper in order to choose.