Start with bank and credit card reconciliation, working month by month from the earliest unreconciled period forward. This is the foundation because everything else depends on accurate account balances. Don’t skip ahead to recent months. If January is off, every month after it will be off too. QuickBooks Online shows the last reconciled date for each account, so you know exactly where to pick up.

Next, fix uncategorized transactions. These are the ones sitting in “Uncategorized Expense” or “Uncategorized Income” because nobody knew where to put them. Go through each one and assign the correct category based on the vendor, amount, and any available documentation. This part is tedious but necessary because uncategorized transactions make your financial statements meaningless.

Clear out the “Ask My Accountant” or suspense account. This is where transactions get dumped when someone doesn’t know the right category. Every dollar in that account needs to be moved to the correct place on your chart of accounts. While you’re at it, review and clean up the chart of accounts itself. Messy files often have duplicate accounts, misspelled names, or accounts created on the fly that don’t belong. Consolidate duplicates and rename things so your reports actually make sense when you read them.

Reconcile your opening balances. If the QuickBooks file was set up incorrectly or migrated from another system, the opening balances may not match your actual bank statements or prior tax returns. This is easy to miss and it throws off everything downstream.

Clean up duplicate vendors and customers. QuickBooks lets you merge duplicates, which tidies up your records and makes 1099 reporting and accounts receivable tracking accurate. Then produce a trial balance and verify it against your most recent tax return. If the two don’t match, something is still wrong and needs investigation. QBO’s audit log is helpful here because it shows who changed what and when, which helps you trace where things went sideways.

This process can take anywhere from a few hours to several weeks depending on how far behind things are and how many accounts are involved. If you’re dealing with more than a few months of neglected books, catch-up bookkeeping is worth considering because mistakes made during cleanup can create new problems that are harder to find later. A file that’s been messy for a year or more usually has errors layered on top of each other.

The goal isn’t just to make the file look clean. It’s to get your numbers accurate enough that you can trust them for decision-making and tax filing. Many Phoenix bookkeepers see files where someone attempted a cleanup but skipped reconciliation or didn’t verify against tax returns, and the books still don’t reflect reality. Do it in order, verify at the end, and you’ll have a file you can actually rely on going forward.