If I open a small business checking account and use it as a personal account, do I get taxed different?

I would just close it. Generally banks charge more for business checking, whether account fees, minimum balances, or price of checks. You should not have to pay for a personal checking and you can probably get better interest and maybe free checks. As far as the taxes go I believe it will be how you work it out with your accountant. As in your taxable income has nothing to do with your checking (as far as the IRS goes). So it will be legitimate income versus legitimate expenses will leave you with taxable income. Simple answer: way more clean to start the new account.