An LLC is a business structure under state law. For taxes, though, an LLC gets to choose how it's treated — and that decides which return you file and when.
Single-member LLC
By default, the IRS doesn't treat it as a separate taxpayer. Business income and expenses go on your personal return on Schedule C (Form 1040). You also pay self-employment tax (Social Security and Medicare) on the profit — Schedule SE.
Multi-member LLC
By default, it's taxed as a partnership. The company files Form 1065, and each owner receives a Schedule K-1 with their share of the profit to report on their personal return. The deadline for a calendar year is March 15.
LLC electing S-Corp status
An LLC can file Form 2553 to be taxed as an S corporation. It then files Form 1120-S (also by March 15), the owner takes a reasonable salary through payroll, and the rest of the profit passes through on a K-1. At certain profit levels this can lower self-employment tax — but it adds bookkeeping costs. Whether it pays off for you is worth calculating individually.
LLC electing C-Corp status
A less common option: the company files Form 1120 and pays corporate tax itself. The deadline is April 15.
What about Illinois
- Partnerships file IL-1065, S corporations file IL-1120-ST, corporations file IL-1120
- Partnerships and S corporations in Illinois also pay a replacement tax
- Separately from taxes, an LLC files an annual report with the Secretary of State every year
Taxes during the year
Business owners usually pay tax in advance through quarterly estimated payments in April, June, September and January. This helps avoid penalties and a large bill in April.
This article is general information, not tax advice. Your situation may differ — book a consultation for an answer specific to you.