The forms you need to file come down to how your business is structured. Each entity type has its own primary tax return, and most businesses have additional filing requirements on top of that.

If you’re a sole proprietor or single-member LLC, you file Schedule C along with your personal Form 1040. All your business income and expenses flow onto your individual return. You’ll also need Schedule SE to calculate self-employment tax, which covers Social Security and Medicare on your net business profit.

Partnerships and multi-member LLCs file Form 1065. This is an informational return, meaning the partnership itself doesn’t pay income tax. Each partner receives a Schedule K-1 showing their share of income and deductions, which then goes on their personal return.

S corporations file Form 1120-S. Like partnerships, the S-corp passes income through to shareholders via K-1s. But if you’re an owner who works in the business, the S-corp must also run payroll for you and file quarterly payroll returns.

C corporations file Form 1120 and pay tax at the corporate level. Shareholders report any dividends separately on their personal returns, which is where the double taxation issue comes in.

Beyond the main return, there are several forms that apply to most small businesses regardless of entity type. Form 941 is filed quarterly if you have employees, reporting wages paid and taxes withheld. 1099-NEC forms are due for any contractor or vendor you paid $600 or more during the year. If you’re a pass-through entity owner, you’ll likely need to make quarterly estimated tax payments using Form 1040-ES to avoid underpayment penalties.

One detail that catches Tennessee business owners off guard is the franchise and excise tax. Tennessee doesn’t tax personal income, but most LLCs, S-corps, and C-corps doing business in the state owe franchise and excise tax. This is a separate filing that’s easy to overlook if you assume no state income tax means no state business tax.

Getting the right forms filed on time matters more than most owners realize. Late filings trigger penalties that add up quickly, especially for informational returns like the 1065 and 1120-S where the penalty is assessed per partner or shareholder per month. If you’re unsure which forms apply to your situation, working with someone who handles small business tax returns regularly will save you from missed deadlines and unexpected penalty notices.