How to Catch Up on Bookkeeping When You're Months Behind

TL;DR: Find the last month where every account was reconciled and nothing was left unanswered. That is your starting line. Get every transaction from that month forward into your books, then work one month at a time, oldest first: categorize, resolve the transfers and personal items, reconcile, move on. Keep a running list of the questions only you can answer. If you'd rather not do it yourself, TidyMonth by Prosper starts with a free Books Check that shows how far behind you are and what the catch-up would cost.

You stopped opening the bookkeeping software sometime in the spring. It's now the fall. Your CPA has asked for records, or a lender has, or you just want to know what the business actually made this year.

This is one of the most common situations a small service business ends up in. In Bluevine's 2026 survey of 785 US small-business owners, 42% named bookkeeping as their largest weekly time drain. When something is the biggest drain on your week, it's the first thing to get skipped, and skipped weeks turn into skipped months.

The good news is that catching up is a mechanical process. Most of it is the same work every time. Here is how to do it in any bookkeeping software, then how Prosper changes the work, then what TidyMonth does if you'd rather hand it off.

Step 1: Find the last month you can trust

Don't start with the pile. Start by finding the edge of the pile.

Go account by account: checking, savings, every credit card, every payment processor like Stripe or PayPal. For each one, find the last month where two things are true:

1. The account was reconciled. Your books' balance on the last day of the month matched the statement balance.
2. Nothing in that month was left uncategorized or marked "ask my accountant."

The most recent month where every account passes both tests is the month your books are reliable through. Everything after it is the catch-up.

Write that month down. If different accounts stop at different months, the earliest one is your starting line, because a month isn't finished until every account in it is finished.

Step 2: Get every transaction in

Before you categorize anything, make sure the transactions exist in your books.

If your bank feed is connected, check how far back it pulled. Many feeds only bring in 90 days on first connection. Anything older has to come in another way.

If there's a gap, download a CSV from the bank for the missing period and import it. Most bookkeeping software accepts a CSV of date, description, and amount.

Then check the count. Open the bank statement for one of the missing months and count the transactions. Compare with what's in your books for that month. If the numbers don't match, you either have a gap or a duplicate. Fix that before going further, because every other check depends on the transactions being there exactly once.

A common trap: importing a CSV for a period the bank feed already covered. Now every transaction in the overlap is in twice. If you see revenue that looks too high, this is the first thing to look for.

Step 3: Work one month at a time, oldest first

Now categorize. Take the first month after your reliable-through month and work only that month.

Group by merchant. Sort the month's transactions by description. Once you decide what a vendor is, apply the same category to every transaction from that vendor. Your hosting bill is the same category in March as in August.

Handle transfers separately. Money moving from your checking account to your savings account, or a payment to your credit card from your checking account, is not income and not an expense. It's a transfer. Match both sides. Booking a transfer as revenue is one of the most common ways catch-up books end up wrong. We cover this in detail in Money Moved Between Your Own Accounts. Did Your Books Call It a Sale?

Pull out the personal items. A personal purchase on the business card is not a business expense. Mark it as an owner's draw, which is the accounting term for money the owner took out of the business. Your CPA decides how it's treated at tax time. Your job is to make sure it isn't sitting in "office supplies."

Put the unknowns on a list. Some transactions you won't remember. An Amazon order from five months ago. A $340 charge from a vendor name you don't recognize. Don't guess. Put them on a question list with the date and amount, and keep going. Guessing now means cleaning up later.

Step 4: Reconcile the month before you move on

When the month is categorized, reconcile it. Take the statement's closing balance and compare it to your books' balance on that date.

If they match, the month is done. Move to the next one.

If they don't match, the difference is a clue. A difference equal to one transaction you recognize is usually a missing entry. A difference equal to double a transaction is usually a duplicate. A difference that looks like a round number is often a transfer that only got recorded on one side.

Reconcile every month individually. It's tempting to categorize eight months and then reconcile once at the end, but a mismatch across eight months is much harder to find than a mismatch in one.

Step 5: Resolve the question list

By the end you'll have a list of transactions only you can explain. Sit down with it once. Check your email for receipts. Check the vendor's website for an order history. Ask the client whether that deposit was theirs.

What's left after that goes to your CPA as an open question. It's better to hand over three honest unknowns than thirty guesses.

Step 6: Set a routine so it doesn't happen again

The catch-up is done when every month reconciles and the question list is empty or handed off. The next problem is not falling behind again.

The routine that works for most small service businesses is once a month: pull in the transactions, categorize by merchant, resolve transfers and personal items, reconcile, and answer the questions. Put it on the calendar for the same day each month. Catching up on one month is an hour or two. Catching up on eight is a project.

How this works in Prosper

Prosper is the platform TidyMonth uses to do this work, and you can use it yourself with your CPA.

The steps are the same. The difference is how much of each step you touch.

Getting transactions in. Connect your bank and card accounts through Plaid, forward receipts by email, or import a CSV. Prosper reads your accounts by default and changes nothing in them.

Categorizing. Prosper scans the activity and groups it into decisions. Your recurring hosting bill, your usual software subscriptions, the client deposit that matches an invoice: those get grouped and proposed together. You approve, change, or ask your CPA. Prosper asks about the things it can't infer, and it shows you the decision and the evidence before anything is applied. Every change is reversible.

Transfers and personal items. When two transactions look like the two sides of a transfer, Prosper shows them together and asks you to confirm. When a purchase looks personal, it asks instead of guessing.

The question list. The unknowns don't go on a separate spreadsheet. Each one stays attached to its transaction as an open question, with whatever receipt or note you've added. When you're ready, Prosper prepares a CPA packet: the transactions, the decisions, the evidence, and the open questions, in one place your accountant can review.

What Prosper does not do is make the accounting or tax calls. You provide the business context. Your accountant reviews the accounting and tax treatment.

If you'd rather hand it off: TidyMonth by Prosper

Some owners read the steps above and think, fine, I'll do that this weekend. Others think, I'd rather pay someone.

TidyMonth by Prosper is the monthly bookkeeping service for the second group. It starts with a Books Check, which is free. You connect your accounts, and the Books Check shows which month your books are reliable through, how many months need catch-up, what was checked, and what couldn't be verified from the records available. Nothing in your accounts is changed during the check, and there's no card required.

If your business fits, you get a scoped price on the spot. Up to three months of catch-up is included with the $199 per month subscription. Four to six months is $399. Seven to twelve months is $799. More than that, or more than three active accounts, or more than about 300 transactions a month, gets looked at by a person who sends a fixed price. You see the number before you pay anything.

After the catch-up, TidyMonth handles the agreed monthly bookkeeping in Prosper. A bookkeeper reviews each close. You answer the business questions that need your input, the same question list from Step 5, without doing the rest.

If the first monthly close isn't worth it, the first $199 payment is refunded in full. You can cancel in one click, and your books export in full at any time.

What your CPA still decides

Catching up gets the records complete and reconciled. It does not decide how anything is treated for tax. Whether an owner's draw is a distribution or something else, whether a purchase is an asset or an expense, how a filed year gets corrected: those are your CPA's calls. Prosper and TidyMonth prepare the records and the questions. Your accountant reviews and decides.