The bookkeeping mistake that costs small businesses thousands
Mixing personal and business expenses is common — and it’s quietly eating into your deductions.
The most common bookkeeping mistake we see is also the most expensive: mixing personal and business expenses in the same account.
When your business expenses run through your personal checking account (or vice versa), it becomes nearly impossible to track what’s deductible. At tax time, your CPA is left guessing — or you’re spending hours sorting through transactions trying to remember which lunch was a client meeting.
The result is missed deductions. If you can’t clearly prove an expense was business-related, you can’t deduct it. Over a year, those missed deductions add up to thousands of dollars in higher taxes.
The fix is simple: open a separate business checking account and a business credit card. Run all business expenses through those accounts. Everything else stays personal.
This one change makes your bookkeeping cleaner, your deductions defensible, and your tax preparation faster and cheaper. It also protects your personal assets if your business ever faces a legal issue.
If you’re currently commingling accounts, don’t panic. Start separating them now — there’s no need to retroactively fix everything. We can help you set up a clean system going forward and sort through the current year’s transactions at tax time.