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The Monthly Bookkeeping Checklist That Keeps a Year Clean
Bookkeeping goes wrong slowly. A month that is never closed becomes a quarter nobody trusts, and then a filing season spent reconstructing a year from bank statements. The routine below prevents that.
Most small business bookkeeping problems are not caused by one dramatic mistake. They are caused by a month that was almost finished, then the next one starting. A year later the profit and loss shows numbers nobody can explain, a lender wants statements, and the work of reconstructing twelve months costs several times what keeping up would have.
This is the routine that prevents it. It is not complicated. It just has to actually happen, every month, in roughly this order.
Every month
Bring every transaction in
Every bank account, every credit card, every payment platform. If money moved through it, it belongs in the books — including the account you only use occasionally, which is where the surprises usually live.
Code consistently, not creatively
The categories on your profit and loss have to mean the same thing in December as they did in January, or a year of data cannot be compared. Where a transaction genuinely does not fit, decide once and stay with it. Bank feed rules are useful for repeating items, and worth reviewing periodically — a rule that quietly miscodes for six months is hard to spot.
Reconcile to the statement
This is the step that separates books you can rely on from books that merely look finished. Every bank account, credit card and loan gets tied to its statement, with the ending balance matching.
When something does not reconcile, find out why. Do not post an adjustment to force it. A plug makes the reconciliation report look clean while preserving the error underneath, and that error will still be there at year end, larger and harder to trace.
Keep owner money separate
Owner draws and contributions are not income and expenses, and personal spending on a business card is not a business deduction because it went through a business account. Coding these correctly protects the deductions that are legitimate, and it matters more than most owners expect if the business is ever examined.
Review what is outstanding
Look at who owes you and how long it has been, and at what you owe. Undeposited funds and clearing accounts should empty out rather than accumulate — a balance sitting in either is almost always an error rather than a real asset.
Read the statements, then close
Look at the profit and loss against last month and the same month last year, and at the balance sheet for anything that has drifted. You are looking for the thing that does not make sense — a category that doubled, an asset that appeared, a liability that never moves.
Then close the period in your accounting software. Closing stops a reported month from being edited later, which is what makes a statement you gave to a lender still true a month afterward.
Every quarter
- Check estimated tax payments against how the year is actually going, rather than against last year's number.
- Reconcile payroll filings to what the books show for wages and taxes.
- Review sales and use tax if you collect it, including any new states you have started selling into.
- Look at the fixed asset list for anything bought that was expensed by mistake, or expensed that should have been capitalized.
Once a year, before the return
- Confirm every loan balance against a year-end statement, and that the principal and interest split is right.
- Confirm the depreciation schedule matches what is actually owned and in service.
- Confirm contractor payments and that 1099s go out on time.
- Review the chart of accounts and retire categories nobody uses.
If you are already behind
Catching up is normal and it is not a reason to avoid the conversation. The order that works is oldest first: reconcile the earliest unreconciled period, then move forward, because an error in an early month propagates through every month after it. Fixing the most recent month first feels productive and usually has to be redone.
It is also worth being honest about which years actually matter. If a prior year's return was filed from books that were never reconciled, the useful question is whether the return was right, not whether the file is tidy.
Why this is worth the hour
Clean books are not an accounting virtue for its own sake. They are what lets you see a margin slipping in July rather than the following April, what a lender asks for, what makes a tax return defensible instead of approximate, and what a buyer will eventually look at. The monthly routine is the cheapest version of all of that.
The information on this site is general in nature and is not tax, legal, or accounting advice for your situation. Tax law changes and the right answer depends on facts we would need to review with you. Please speak with a qualified professional before acting on anything you read here.
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