The first year of filing taxes of an LLC is an adventure in unearthing the information that wasn't shared elsewhere. The forms themselves are simple. The trick is that all the obligations began months ago, with estimated payments due every quarter and the deduction that would save the most money due in December after making the election.
The forms filed depend on the classification of the LLC. The IRS does not have a category of "LLCs" to which you file taxes. You pay as a sole proprietor, a partnership, an S-Corporation or a C-Corporation, depending on your formation and elections.
In this guide we discuss the tax filing of an LLC for each category, the deadlines, the calculation, and the 5 most costly mistakes in the first year of an LLC.
The expensive mistake is almost never on the return. It's the quarterly estimates that weren't paid, so the first filing comes with a penalty attached and a bill the business hasn't reserved for. The safe harbour rule solves this and most first-year owners have never heard of it, pay in the equivalent of last year's tax liability across the four quarters and you're protected from the penalty regardless of what this year turns out to be.
Anu Gupta, CA, EA, B.Tech · LinkedInUnderstanding LLC Tax Classifications
Before you can file, you need to know how your LLC is classified for federal tax purposes. The IRS does not recognise 'LLC' as a tax classification, it taxes LLCs based on their structure and any election made:
| LLC Type | Default Federal Tax Treatment | Forms Filed |
|---|---|---|
| Single-member LLC (no election) | Disregarded entity, taxed as sole proprietor | Schedule C (Form 1040) |
| Multi-member LLC (no election) | Partnership | Form 1065 + Schedule K-1 per member |
| LLC elected as S-Corp | S-Corporation | Form 1120-S + Schedule K-1 per shareholder |
| LLC elected as C-Corp | C-Corporation | Form 1120 |
Most first-time LLC filers are single-member LLCs with no special election, they file Schedule C as part of their personal Form 1040. This guide focuses primarily on that scenario.
Step-by-Step Process for Filing LLC Taxes
- Step 1: Gather records, bank statements, receipts, income records, mileage logs, home office measurements (if applicable). Organised bookkeeping throughout the year makes this step straightforward; catch-up bookkeeping in January is expensive and error-prone
- Step 2: Separate business from personal, if you have mixed any personal expenses with business, do this now. Only legitimate business expenses are deductible
- Step 3: Calculate net profit, total income minus total deductible business expenses = net profit (what you report on Schedule C)
- Step 4: Calculate self-employment tax, net profit x 92.35% x 15.3% (up to SS wage base) = SE tax. Use Schedule SE
- Step 5: Deduct half the SE tax, you can deduct 50% of your SE tax from gross income on Form 1040 (above-the-line deduction)
- Step 6: Consider deductions, home office (Form 8829 or simplified method), retirement contributions (SEP-IRA, Solo 401k), health insurance premiums (deductible above-the-line for self-employed), vehicle expense (actual cost or standard mileage rate)
- Step 7: File on time, see deadlines below
Tax Filing Deadlines for 2026
The following deadlines apply for the 2025 tax year, filed in 2026:
| LLC Type | Filing Deadline (2026) | Extension Deadline |
|---|---|---|
| Single-member LLC / sole proprietor (Form 1040 + Schedule C) | April 15, 2026 | October 15, 2026 |
| Multi-member LLC / Partnership (Form 1065) | March 16, 2026 (March 15 is Sunday) | September 15, 2026 |
| LLC taxed as S-Corp (Form 1120-S) | March 16, 2026 (March 15 is Sunday) | September 15, 2026 |
| LLC taxed as C-Corp (Form 1120) | April 15, 2026 | October 15, 2026 |
Quarterly estimated tax payments for 2026 are due:
| Payment Period | Due Date |
|---|---|
| Q4 2025 (Jan-Mar) | January 15, 2026 |
| Q1 2026 (Jan-Mar) | April 15, 2026 |
| Q2 2026 (Apr-May) | June 15, 2026 |
| Q3 2026 (Jun-Aug) | September 15, 2026 |
Common Mistakes First-Time LLC Filers Make
- Skipping quarterly estimated payments: the IRS expects taxes paid as you earn. If you owe more than $1,000 in federal taxes at year-end, you likely owe an underpayment penalty, currently 7% a year, compounded daily
- Mixing personal and business expenses: any personal expenses paid from the business account are not deductible and complicate the return. Keep accounts strictly separate from day one
- Claiming the home office deduction incorrectly: you can only deduct a home office if it is used regularly and exclusively for business, a desk in a shared room does not qualify
- Not deducting 50% of self-employment tax: many first-time filers miss this above-the-line deduction on Form 1040, it directly reduces adjusted gross income
- Missing retirement contribution deadlines: SEP-IRA contributions can be made until the tax filing deadline (including extensions), a powerful last-minute deduction for profitable LLC owners
Book a free consultation and we will get the books ready for it.
Frequently Asked Questions
Does an LLC file a separate tax return?
It depends on classification. A single-member LLC with no election files Schedule C inside the owner's personal Form 1040 with no separate return. A multi-member LLC files Form 1065, but pays no tax itself; income passes to members on Schedule K-1 and is taxed on their personal returns. An LLC electing S-Corp or C-Corp status files its own return in both cases.
What forms do I need for a single-member LLC?
Schedule C for profit and loss, Schedule SE for self-employment tax, and Form 1040. Add Form 941 quarterly, Form 940 annually and W-2s if you have employees. Add Form 1099-NEC for any contractor you paid $600 or more. If you're claiming a home office under the regular method, Form 8829 as well.
Can I file LLC taxes myself?
A single-member LLC with clean books, one income stream and straightforward expenses is manageable with tax software. It stops being manageable once you have employees, operate in multiple states, hold inventory, or are anywhere near an S-Corp election, at that point a CPA usually recovers their fee through the decisions they make rather than the forms they complete.
What if I didn't make any quarterly payments in my first year?
File anyway, pay what you owe, and expect a penalty on the underpaid amount. It's calculated on how much was unpaid and for how long, so filing and paying sooner reduces it. Then set up estimates for the current year immediately, the prior-year safe harbour is available to you now that you have a return showing self-employment income, which makes the second year far simpler than the first.
Do I still file if the LLC made no money?
Usually yes. A single-member LLC with no activity may have nothing to report on Schedule C, but a multi-member LLC generally files Form 1065 regardless, and state annual reports and franchise taxes are due whether or not the business traded. Dormant doesn't mean exempt, and missed filings cost your good standing.
Written by
Anu Gupta, CA, EA, B.Tech
Anu works with US businesses on tax and entity questions at Profitjets, from choosing a structure to the filings that follow it. She writes about the decisions owners make once and then live with for years. Connect on LinkedIn
Free consultation
First Return Coming Up?
Book a free consultation and we will get the books ready for it.