Fixing your books
12 bookkeeping mistakes small businesses make (from someone who fixes them)
Cleanup work gives a bookkeeper an education: you see the same mistakes over and over, in different fonts. None of them come from stupidity. They come from busy owners doing their best inside software that assumes they had training. Here are the 12 I find most often, why each one hurts, and what fixing it looks like.
1. Skipping reconciliation
The most common mistake, and the quietest. Reconciliation means matching your books against your bank statements until they agree. Nothing visibly breaks when you skip it, so busy owners skip it, and the books drift from reality one small error at a time. By the time anyone notices, the drift is a season’s worth.
The fix: reconcile every account, every month, against the statement. Non-negotiable, and the first thing I check in any file.
2. Counting money that isn’t income
Loan deposits, transfers between your own accounts, refunds you issued that never got recorded: each one can masquerade as revenue. The result is overstated income, which means overstated taxes and decisions based on a business that looks healthier than it is. This is the mistake I most hate finding, because it means the owner has been paying for it invisibly.
The fix: every deposit gets identified. Income, loan, transfer, or owner contribution; they’re different things and your books should know the difference.
3. Mixing business and personal spending
The business card at the grocery store, the personal card at the supplier. It blurs your profit picture, weakens your tax position, and can undermine your LLC’s liability protection. It’s common enough that I wrote it its own article.
The fix: dedicated business accounts, everything through the right door, and a cleanup for the tangled history.
4. Letting “Uncategorized” become a filing system
A handful of uncategorized transactions is normal. Hundreds of them, or a swollen “Ask My Accountant” account, means your reports describe a business where a big slice of the money is a mystery.
The fix: categorize as you go, or better, on a monthly rhythm with someone who asks you the 4 questions that empty the pile.
5. DIY payroll entries
Payroll providers do the paying and filing well. The bookkeeping entry is where things go sideways: gross wages, employer taxes, and withholdings each belong in specific places, and a hand-typed “payroll $8,412” entry puts them nowhere. The books stop matching the filings, and year-end becomes a puzzle.
The fix: payroll recorded to match the provider’s reports, every run. It’s precise, unglamorous work, which is why it’s a service.
6. Booking loan payments as pure expense
A loan payment is 2 things: principal (reducing what you owe) and interest (an expense). Booked entirely as expense, your P&L overstates costs and your balance sheet still shows debt you’ve partly paid.
The fix: split every loan payment according to the loan statement. Your reports get more accurate in both directions at once.
7. Trusting the bank feed blindly
Bank feeds are a gift, and they make 2 kinds of trouble: duplicates (a feed hiccup imports a week twice) and wrong auto-categorization (the software’s guess becomes permanent record). Feeds are raw material, not finished books.
The fix: feeds reviewed by a person, and reconciliation as the backstop that catches what slipped through.
8. No paper trail for the weird stuff
The $3,000 equipment purchase from a guy on Facebook Marketplace. The month you covered payroll from personal savings. Unusual transactions are fine; undocumented unusual transactions become unanswerable CPA questions 14 months later.
The fix: a note and a receipt at the moment it happens. Your future self, your bookkeeper, and your tax preparer all thank you.
9. Missing quarterly tax payments
A lot of owners simply do not set the money aside. There is no budget line for it, the quarter arrives, the cash is not there, and now you are looking at penalties and interest on top of a bill you already owed. This one is pure planning. Money set aside on a schedule turns a recurring crisis into a transfer you barely notice.
10. Borrowing from payroll taxes
This one deserves its own warning, because it is the mistake that stops being about money and starts being about your personal exposure.
This did not happen to me; it happened to an associate. He caught a contractor who was low on cash at the end of the month and decided he could not make some of his payroll taxes. The plan was to hold that money aside and catch up later.
The IRS does not look fondly on this. There is a thing called the trust fund recovery penalty. The short version: the money withheld from your employees’ paychecks is not your money, it is money you are holding in trust for them. If a business intentionally uses employee tax withholdings to pay expenses, the IRS can bypass some of the liability protections your business structure provides and hold the responsible people personally liable.
Read that again, because it undoes the thing your LLC exists to do. That is the kind of situation that can really ruin your life, and it usually starts as a temporary cash decision on a bad month. If you are in it, correct it immediately, and get your CPA involved today, not next quarter.
11. Nobody matching bills to reality
Scams keep getting more sophisticated. Fake invoices show up looking exactly like real ones, from vendors you actually use, in months you actually ordered from them.
The defense is unglamorous: somebody matches accounts payable and bills against what was actually ordered and actually delivered. Does this match? Does this match? Does this match?
Business owners get caught up in the flow of running the business day to day, and they do not always have time to go back and check line by line. And if you are doing that checking at 11pm, the question worth asking is whether you could be working in your business instead, and handing off the paperwork.
12. Producing reports nobody reads
The subtlest mistake: books maintained just well enough to generate reports that go straight into a folder. If you can’t say whether last month made money, the bookkeeping isn’t finished; it’s just filed.
The fix: reports explained until they’re useful. It’s my favorite part of the job, and the part I’d tell you to demand from any bookkeeper: understanding your numbers, not just receiving them.
Where to start
If you found your books in more than 2 items on this list, don’t start with guilt. Almost all of these are ordinary, and I fix them every month. The payroll tax one is the exception: if that is you, call your CPA today, because it gets worse with time in a way the others do not.
For everything else, start with a review. A good bookkeeper looks first, tells you what’s there, and quotes the fix before touching anything. Whatever shape the file is in, I’ve seen worse.
Quick answers
What is the most common bookkeeping mistake?
Skipped reconciliation. Owners stop matching their books against bank statements because nothing visibly breaks, and the books drift a little further from reality every month until the reports can't be trusted.
What bookkeeping mistakes cost the most money?
Overstated income and missed deductions, because both flow straight into your tax bill. Counting loan deposits or transfers as revenue means paying tax on money that was never income.
What is the trust fund recovery penalty?
It is how the IRS treats unpaid payroll tax withholdings. Money withheld from employee paychecks is held in trust, not owned by the business. If a business intentionally uses those withholdings for expenses, the IRS can bypass some of the liability protections of your business structure and hold responsible individuals personally liable.
How do I know if my books have mistakes?
Run 3 checks: does your book balance match the bank after pending items, was every account reconciled recently, and does your P&L match your lived sense of the business? A no on any of them deserves a professional review.
Should I fix bookkeeping errors myself?
Recent, isolated errors, yes. Systemic ones, like months of miscategorization or misbooked payroll, compound when patched piecemeal. A one-time professional cleanup with documentation usually costs less than the DIY hours it replaces.