Costly Bookkeeping Mistakes Businesses Made in 2025
If you’re doing your own bookkeeping, chances are you’re not doing it wrong — you’re just missing a few key details no one ever explained clearly.
As I reviewed 2025 financial records, the same bookkeeping mistakes showed up again and again. Not because business owners were careless, but because these issues quietly compound until they cause stress, confusion, or tax-time panic.
If you’re just getting started, you may also want to read The First 3 Things to Do When You Start Your Books.
Let’s walk through the most common (and costly) bookkeeping mistakes I saw — and how you can fix or avoid them going forward.
1. Mixing Personal and Business Expenses
The mistake:
Personal meals, subscriptions, or travel were paid directly from the business account. This makes reports inaccurate and deductions harder to support.
Why it matters:
When personal and business expenses are mixed, your financial reports stop telling the truth, which can cause issues if you’re ever audited under IRS rules for business expenses.
The fix:
Keep separate personal and business accounts and cards. If something personal slips through (it happens), reclassify it correctly right away instead of leaving it messy.
2. Payroll Set Up With Outdated Tax Rates
The mistake:
Payroll was run using old tax rates or without accounting for new requirements, leading to underpayments and scary notices.
Why it matters:
Payroll errors don’t just fix themselves — they snowball and often come with penalties.
The fix:
Review payroll settings regularly, especially at the beginning of the year. Confirm tax rates, thresholds, and filing requirements are current.
3. Expensing Big Purchases Instead of Depreciating Them
The mistake:
Equipment or large software purchases were fully expensed instead of depreciated.
Why it matters:
This distorts profit and can create issues in future years when the numbers no longer line up.
The fix:
Identify large purchases early and track them properly so depreciation is recorded over time.
4. Recording Sales Tax as an Expense
The mistake:
Sales tax collected from customers was recorded as an expense, reducing reported profit incorrectly.
Why it matters:
Sales tax is not your money — it’s a liability you’re holding temporarily, and it must be tracked correctly under sales tax reporting guidelines.
The fix:
Record sales tax as a liability (not an expense) and reconcile it before filing returns.
5. Recording Loans as Income
The mistake:
Business loans or lines of credit were recorded as income, inflating revenue and tax exposure.
Why it matters:
Loans increase cash — not income. Treating them incorrectly makes your business look more profitable than it really is.
The fix:
Record loans as liabilities so your reports reflect true operating income.
6. Falling Behind on Reconciliations
The mistake:
Bank and credit card accounts were months behind, allowing errors to pile up unnoticed.
Why it matters:
Monthly reconciliations are a core part of SBA bookkeeping best practices and help prevent small errors from becoming big problems.
The fix:
Reconcile accounts monthly. It’s the simplest way to catch mistakes early and stay in control.
Not sure if any of these mistakes apply to you? Take the Bookkeeping Ready Quiz to quickly see where your bookkeeping habits may need attention.
Final Thoughts
If you want 2026 to feel calmer, clearer, and more confident, now is the time to fix what didn’t work last year.
You don’t need perfection — you need systems that support you, accurate numbers, and habits that keep things from spiraling.
That’s exactly what Kristin’s Bookkeeping Corner is here for 💜
If you want help fixing these issues step by step, start with my free Bookkeeping Starter Kit, designed for business owners who manage their own books.