--- title: "How to Fix a Prior-Year Error in Your Books | MCC Solutions" description: "Size the error, then fix it with a current-period adjusting entry where allowed, so your books still match the filed return. Duplicate bank feed example." url: "https://mcc-solutionsnj.com/bookkeeping/guides/correcting-prior-year-errors-in-your-books" --- Bookkeeping guide · Updated October 12, 2026 # Correcting Prior-Year Errors in Your Books Safely Finding an error in last year's books is common, especially after a cleanup. The temptation is to open the old period and fix it directly. That can create a mismatch between your books and the return already filed. A careful method keeps everything consistent. By [Matthew Coleman](/about), MCC Solutions **Quick answer.** Before fixing an error in last year's books, work out what happened and how big it is. A misclassified expense may change nothing on the return, but a missed income item or a doubled expense changes profit. Do not just reopen the old period and edit it. Want this handled for you? Monthly bookkeeping, cleanup and year-end close for small businesses. Start with a free health check of your books. [Free health check](/bookkeeping/health-check)[Get a quote](/bookkeeping/#interest) **Related:** [Void vs delete a transaction](/bookkeeping/guides/voiding-vs-deleting-transactions) · [NJ 1099 contractor rule (ABC test)](/bookkeeping/guides/nj-independent-contractor-rule-abc-test-2026) · [Trial balance explained](/bookkeeping/guides/trial-balance-explained) **Free tools:** [Current ratio calculator](/bookkeeping/current-ratio-calculator) · [ROI and payback calculator](/bookkeeping/roi-and-payback-calculator) [![Intuit ProAdvisor Gold tier badge](/img/credentials/intuit-proadvisor-gold.png)](https://proadvisor.intuit.com/app/accountant/search?searchId=matthew-coleman77)Gold tier in Intuit's ProAdvisor program. [See my Intuit listing](https://proadvisor.intuit.com/app/accountant/search?searchId=matthew-coleman77) Keeping your own books? Tallyfinch does invoices, bank import and reports on your computer. [See Tallyfinch](/bookkeeping/mcc-books-downloadable-bookkeeping-software) ## First, size and classify the error Work out what happened and how big it is. A misclassified expense, where the right amount went to the wrong category, may change nothing on the return. A missed income item or a doubled expense changes profit. A transaction booked in the wrong year affects two periods. Write a one-paragraph description and list the accounts and amounts involved. Ask your preparer whether the error affects the filed return. If it does, the amendment discussion comes before the books are touched. ## Prefer a current-period adjusting entry when allowed Many corrections can be recorded as an adjusting entry dated in the current year, with a memo explaining that it corrects a prior-year item. This leaves the filed year untouched. Whether that is appropriate depends on the size, the tax effect and your preparer's advice, so confirm before using it. When the correction does need to reach the old period, work with your preparer on the dates and whether the closed period lock should be lifted. ## Handling the opening balances Retained earnings and equity opening balances should tie to the prior filed return. If you change a closed year, the opening balance of the next year changes too, and everything after it flows through. Compare the balance sheet to the filed return after any change. Bank, loan and other balance sheet accounts should always agree with outside statements. If an error is in one of these, reconcile it first, because other fixes depend on it. ## Want us to handle it? We get behind or messy books current, tell you what we found, and hand you a clean starting point, in QuickBooks, Xero or Excel. **Price:** Free review of your books first, then a written quote before any work starts. [Get a free review and quote](/bookkeeping/#interest) [How catch-up and cleanup work](/bookkeeping/catch-up) ## Document each fix For every correction, write what was wrong, how it was found, the entry made, who approved it and the date. Store the note with the reconciliation or the year-end file. Auditors and buyers read these notes and trust books more when they see disciplined corrections. Avoid deleting transactions in closed periods. Deleting erases evidence. Use reversing entries or voids that leave a record. ## Prevent a repeat Every error has a cause. It might be a duplicated bank feed, a rule that categorizes wrongly or a missing monthly reconciliation. Fix the cause. Add a step to your monthly close to check the area where the mistake occurred. Once things are corrected, lock the period again so the same issue cannot sneak back. ## Example: a duplicated bank feed Imagine a bank feed imported every card charge twice in October of last year, and the duplicate expenses were never noticed. The fix starts by confirming against the card statement, then asking the preparer whether the filed return used the overstated expense. If it did, the correction may involve an amended return, and the books are adjusted in step with that advice. Notice that the books were not edited until the facts and advice were in place. That order protects you from creating a second error while fixing the first. ## Check your work After any correction, rerun the prior-year balance sheet and the current opening balances. Opening equity should equal last year's ending equity, unless you and your preparer agreed on a documented adjustment. Keep a memo describing the error, the correction and who approved it. ## Common questions **Should I tell my preparer about every correction?** Tell them about any that could change the filed return, and keep a note of the smaller ones. They will say what they need. **Is it a problem if my books differ from the filed return?** Differences can be legitimate, such as tax adjustments, but they should be explained. Unexplained differences cause questions. This guide is general information, not tax, legal or accounting advice. Rules, fees and due dates change; check with the IRS, the NJ Division of Taxation or a licensed professional for your situation. Let us handle it [### Monthly bookkeeping Categorizing, reconciling and monthly reports, with cleanup, payroll and NJ filings available. Bookkeeping →](/bookkeeping/) More guides - [Year-End Bookkeeping Checklist for Small Business](/bookkeeping/guides/year-end-bookkeeping-checklist-for-small-business) - [Year-End Inventory Count and Valuation Records](/bookkeeping/guides/year-end-inventory-count-and-valuation-records) - [Year-End Accounts Receivable Review and Bad Debts](/bookkeeping/guides/year-end-accounts-receivable-review-and-bad-debts) - [Prepaid Expenses and Accrued Liabilities at Year End](/bookkeeping/guides/prepaid-expenses-and-accrued-liabilities-at-year-end) Free tool - [Bookkeeping health check](/bookkeeping/health-check) [All guides](/bookkeeping/guides) Reach small business owners, freelancers and bookkeepers who read this guide: [advertise here](/advertise#bookkeeping). Do it yourself ### Month-End Close Workbook A real month-end close in one Excel file. It tells you when a rec does not tie, which variances still need an answer, and when the period is ready to lock. [See what's inside ($19)](/toolkits/month-end-close-workbook)14-day full refund ## Rather have us keep the books? Ask for a quote. [Get a Quote](/bookkeeping/#interest)[Call (908) 444-6373](tel:+19084446373)