You do not have to clean it up before you ask. You do have to stop building on a balance that is not real.
Whatever the business is, the file is not usable while the bank and the credit cards disagree with it. Tax returns, loan applications, and partner arguments all inherit that disagreement. The work does not start by recoding last year's categories into nicer names. It starts by making the cash true. Everything else, inventory, payroll, sales tax, what you owe the owner, waits until a statement and the screen tell the same story. This is the process. It is not a slogan, and it is not a promise about how fast a particular file moves. A file moves as fast as the statements and the unknowns allow.
Send bank statements and credit-card statements for the months that are open, access to the file, and the last return that was actually filed. If payroll is involved, send the payroll reports. If sales tax is involved, send the last filing. You do not need a chart of accounts you are proud of. You do not need to finish the stack of receipts on the passenger seat. Receipts matter for specific questions later. They are not the first move. The first move is the statement, because the statement is the number the bank will not argue with.
Leave the old file in place. A cleanup that begins by starting a new file, with no bridge, throws away the history you may need and hides the difference between what was filed and what the bank did. The return that was filed is a fact. The books should be able to stand next to it and show where they agree and where they do not. Deleting the year to 'start fresh' deletes the comparison.
For each account, the statement balance and the book balance have to meet, with the outstanding items listed rather than plugged. A plug is a journal entry whose only job is to force the number. It makes the month look closed and makes every later month inherit a lie. Outstanding checks and deposits in transit are allowed to be outstanding. They are listed. A difference you cannot name is not closed. It is the work.
Credit cards are the same exercise and are where messy files usually hide. Personal expenses on a business card, business expenses on a personal card, and payments that were coded as expenses instead of as paying down the card: those three things make the card balance nonsense. The first pass names them. It does not lecture you. Personal spending is a distribution to the owner, or a receivable from the owner, depending on what the company is. It is not 'office supplies' just because that was the shortest click.
Categories get repaired after the balances are real, not before. Recoding a transaction that never hit the bank is decorating a ghost. Sales tax you collected, payroll you owe, and loans you are paying down are the next layer, because they are liabilities the cash has been disguising. A loan payment coded as rent, split wrongly between principal and interest, makes both rent and the loan lie. That repair is real, and it is second. First the payment has to be the payment that actually left the bank.
The return waits too. Preparing a return from a file that does not match the statements is how the mess becomes permanent. The person who signs the return needs balances that are true, a list of what is still unknown, and a clear line between business and personal. Giving them a smooth profit and loss with a plug underneath is not helping them. It is handing them your guess.
You get a file whose bank and card accounts agree with the statements, a list of items that are still unknown, and a short map of what that means for the return and for any lender who asks. You do not get a fictional certainty. If a deposit cannot be explained, it stays listed as unexplained. You may be the only person who knows whether it was a loan from a relative, a sale, or a transfer. That question comes back to you in ordinary language, not as a pile of codes.
After that, the monthly habit is small. Match the accounts when the statement arrives. Do not let personal spending sit in a business category for a later version of you to fix. Do not recode a prior closed period just to make a graph look smoother. The relief is that the next due date starts from a balance you can stand on, instead of from a fresh reconstruction every time someone asks how the business is doing.
No. Statements and access to the file are the start. Receipts answer specific questions after the bank matches. Waiting for a perfect shoebox delays the only step that makes the file real.
No. The filed return and the old file are the history. The cleanup has to be able to show where they agree with the bank and where they do not. A brand new file with no bridge hides the difference.
It can be prepared, and it will be a guess. The return should follow a file that matches the statements, with the unknowns listed rather than plugged. A smooth set of numbers with a forced balance underneath is how the same mess shows up next year.
If your file looks like this, start with a free look: small business QuickBooks cleanup.