Navigating the world of small business taxes can often feel like learning a new language, and nowhere is that more apparent than with the alphabet soup of IRS forms. From Schedule C to Form 1120-S, knowing which documents you need to file is the first and most critical step toward a compliant and stress-free tax season. Using the wrong form—or forgetting one entirely—can lead to filing rejections, delays, and potential penalties.
The specific forms your business needs depend almost entirely on your business structure and whether you have employees or work with independent contractors. It’s a roadmap determined by the decisions you made when you first set up your company.
This guide will demystify the most common tax forms your small business will encounter for the 2025 tax year (the return you file in early 2026). We’ll explain what each form is for, who needs to file it, and the key information required, ensuring you have the right documents in hand when it’s time to file.
For a complete guide to deadlines, deductions, and more, be sure to visit our comprehensive 2025 Small Business Tax Season Toolkit.
The Foundation: Income Tax Returns by Business Structure
Your primary tax form is determined by how your business is legally structured. This is the main document you will use to report your income, expenses, and profits to the IRS.
Form 1040, Schedule C: Profit or Loss from Business
Who files it?
- Sole Proprietors: If you run a business by yourself and haven’t formed a legal entity, you’re a sole proprietor.
- Single-Member LLCs: By default, the IRS treats an LLC with one owner as a “disregarded entity,” meaning you file as a sole proprietor.
What is it for?
Schedule C is not a standalone return; it’s an attachment to your personal Form 1040. This is where you report your business’s annual income and subtract all your deductible expenses (like advertising, supplies, and vehicle mileage). The resulting net profit or loss is then carried over to your personal return and taxed at your individual income tax rate. You will also use this net profit figure to calculate your self-employment tax on Schedule SE.
Key Deadline: April 15, 2026
Form 1065: U.S. Return of Partnership Income
Who files it?
- Partnerships: Businesses owned by two or more people.
- Multi-Member LLCs: By default, the IRS taxes an LLC with multiple owners as a partnership.
What is it for?
Form 1065 is an informational return. This means the partnership itself doesn’t pay income tax. Instead, this form reports the business’s total income, deductions, and credits for the year. The partnership also prepares a Schedule K-1 for each partner, which breaks down their individual share of the profits or losses. Each partner then uses their K-1 to report this information on their personal tax return.
Key Deadline: March 16, 2026 (a month earlier than personal returns to give partners time to receive their K-1s).
Form 1120-S: U.S. Income Tax Return for an S Corporation
Who files it?
- S Corporations: Businesses that have filed Form 2553 to elect S-Corp tax status. This can include both LLCs and traditional corporations.
What is it for?
Similar to Form 1065, Form 1120-S is an informational return for a pass-through entity. The S-Corp reports its overall financial performance, and the profits or losses pass through to the shareholders. Like a partnership, the S-Corp issues a Schedule K-1 to each shareholder detailing their portion of the income and deductions. Shareholders use this K-1 to complete their personal tax returns.
Key Deadline: March 16, 2026
Form 1120: U.S. Corporation Income Tax Return
Who files it?
- C Corporations: Businesses structured as C-Corps. This includes LLCs that have elected to be taxed as a C-Corp.
What is it for?
Unlike the other forms, Form 1120 is for a business that pays its own taxes. A C-Corp is a separate taxable entity from its owners. The corporation uses this form to report its income and expenses and calculates the tax it owes based on the corporate tax rate (currently a flat 21%). This is separate from any taxes the owners might pay on dividends they receive.
Key Deadline: April 15, 2026
Essential Forms for Paying Others
Beyond your main income tax return, you’ll likely need to file forms related to how you pay your team. These are sent to both the individual and the IRS.
Form W-2: Wage and Tax Statement
Who files it?
- Any business with employees.
What is it for?
You must issue a Form W-2 to every employee to whom you paid wages and withheld income, Social Security, or Medicare taxes during the year. The W-2 reports the employee’s total annual wages and the amount of tax withheld. You must also send copies of all W-2s to the Social Security Administration along with Form W-3, Transmittal of Wage and Tax Statements.
Key Deadline: January 31, 2026 (to both the employee and the SSA).
Form 1099-NEC: Nonemployee Compensation
Who files it?
- Any business that paid $600 or more to an independent contractor, freelancer, or other non-employee for services during the year.
What is it for?
This form reports the total amount you paid to a contractor. It’s the freelancer’s equivalent of a W-2 and is used to help the IRS track income that isn’t subject to payroll withholding. Before you can issue a 1099-NEC, you must have a completed Form W-9 from the contractor, which provides their name, address, and Taxpayer Identification Number.
Key Deadline: January 31, 2026 (to both the contractor and the IRS).
The Role of Bookkeeping in Accurate Form Filing
Knowing which forms to file is only the first step. The numbers you put on those forms must be accurate and defensible. This is where good bookkeeping becomes indispensable.
Your financial records are the source of truth for every figure on your tax returns:
- For Schedule C: Your categorized expenses in your bookkeeping software directly translate to the deduction lines on the form.
- For Form 1065/1120-S: A clean Profit & Loss statement is required to report total income and expenses before calculating each partner’s or shareholder’s K-1.
- For Form 1099-NEC: Your bookkeeping records should have a clear list of all vendor payments, making it easy to identify which contractors exceeded the $600 threshold.
Trying to fill out these forms from a pile of receipts or un-reconciled bank statements is a recipe for error. Organized, year-round bookkeeping ensures that when it’s time to file, you have reliable, audit-proof numbers at your fingertips.
Don’t Get Lost in the Paperwork
While the sheer number of tax forms can seem intimidating, they are simply the IRS’s way of standardizing financial reporting. By understanding your business structure and your responsibilities for paying others, you can easily identify the forms you need.
The key is not to wait until tax season to get your information in order. Accurate bookkeeping provides the foundation for every number you report, turning a complex puzzle into a simple fill-in-the-blanks exercise. If you’re unsure about which forms apply to you or how to get the right numbers, consulting with a tax professional is always a wise investment.
Ready to prepare for a successful filing? Our 2025 Small Business Tax Season Toolkit has all the resources you need, from checklists to deadline reminders.
Meta Title: What Small Business Tax Forms Do I Need in 2025?
Meta Description: A guide to the essential IRS tax forms for small businesses in 2025, including Schedule C, 1065, 1120-S, 1099-NEC, and W-2. Learn which forms you need.