Getting an EIN does not, on its own, affect your taxes. The nine-digit Employer Identification Number is an identifier the IRS uses to track your business, similar to how a Social Security Number identifies you personally. What changes your tax bill is whatever prompted you to get the EIN in the first place: forming a corporation or partnership, hiring employees, or electing a different tax classification. The EIN simply ties those obligations to your entity in the IRS’s records.
What Actually Changes Your Taxes
The events that require an EIN are the same events that change how you’re taxed. A corporation, partnership, or multi-member LLC needs an EIN because it files its own return. A sole proprietor who hires an employee needs one because payroll taxes have entered the picture. In each case, the tax consequences flow from the structure or activity, not from the number itself.
A single-member LLC is a useful illustration. The IRS treats it as a “disregarded entity” by default, meaning the LLC’s income and expenses land on the owner’s Schedule C exactly as they would for a sole proprietorship.1Internal Revenue Service. Single Member Limited Liability Companies Having an EIN for banking or payroll purposes doesn’t override that. The tax treatment only shifts if the owner files Form 8832 to be taxed as a corporation or Form 2553 to elect S-Corp status.
C-Corporations Pay Their Own Tax
If the EIN belongs to a C-Corporation, the entity files Form 1120 and pays federal income tax at a flat 21% on its net profit.2Internal Revenue Service. Instructions for Form 1120 (2025)3Office of the Law Revision Counsel. 26 U.S. Code 11 – Tax Imposed Shareholders then pay tax again on any dividends they receive. This is the double taxation that defines the C-Corp structure.4Internal Revenue Service. Forming a Corporation
Partnerships and S-Corps Pass Income Through
Partnerships and S-Corporations don’t pay federal income tax at the entity level. The partnership files Form 1065 and the S-Corp files Form 1120-S, and each issues a Schedule K-1 to every owner showing their share of the year’s income.5Internal Revenue Service. About Form 1065, U.S. Return of Partnership Income6Internal Revenue Service. Instructions for Schedule K-1 (Form 1120-S) Owners report that income on their personal Form 1040 and pay tax at their individual rates. To elect S-Corp status, an eligible LLC or corporation files Form 2553, generally within two months and 15 days of the start of the tax year the election should take effect.7Internal Revenue Service. Instructions for Form 2553
The Self-Employment Tax Angle
For most small business owners, the biggest tax question tied to entity choice is self-employment tax. Sole proprietors and single-member LLC owners pay it on their net business income at a combined 15.3%: 12.4% for Social Security on income up to $184,500 in 2026, and 2.9% for Medicare with no cap.8Internal Revenue Service. Self-Employment Tax (Social Security and Medicare Taxes)9Social Security Administration. Contribution and Benefit Base On $100,000 of net profit, that’s roughly $14,130 before any income tax.
Electing S-Corp treatment can reduce that number. An S-Corp owner-employee must draw a reasonable salary subject to FICA, but profits distributed beyond that salary aren’t hit with payroll or self-employment tax. If the S-Corp earns $100,000 and pays a $60,000 salary, only the salary faces FICA; the remaining $40,000 passes through as ordinary income without the 15.3% charge.
The IRS scrutinizes this. Owner-employees who perform more than minor services must receive reasonable compensation before taking distributions, and reclassifying salary as distributions to avoid payroll taxes is a well-known audit trigger. There’s no bright-line test for “reasonable,” but the IRS looks at comparable wages for similar roles, time spent working in the business, and the company’s overall financial picture.10Internal Revenue Service. S Corporation Employees, Shareholders and Corporate Officers
What Changes When You Hire Employees
If you got your EIN because you’re hiring, the tax picture shifts more than in any other scenario. You now collect and remit taxes on the government’s behalf.
FICA
Social Security tax is 6.2% for both employer and employee in 2026, applied to wages up to $184,500. Medicare tax is 1.45% for each side, with no wage cap.11Internal Revenue Service. Instructions for Form 941 – Employer’s Quarterly Federal Tax Return You withhold the employee’s share and pay the matching employer share yourself. For an employee earning $80,000, the combined FICA cost is about $12,240 split evenly. An Additional Medicare Tax of 0.9% applies to employee wages above $200,000; you withhold it but don’t match it.12Internal Revenue Service. Questions and Answers for the Additional Medicare Tax
FUTA
Federal unemployment tax is paid entirely by the employer. The gross rate is 6.0% on the first $7,000 of each employee’s wages, but timely payment of state unemployment taxes generally earns a credit of up to 5.4%, bringing the effective federal rate to 0.6%. That caps out around $42 per employee per year.13Internal Revenue Service. Federal Unemployment Tax
Federal Income Tax Withholding
You also withhold federal income tax from each paycheck based on Form W-4, the employee’s filing status and adjustments, and the IRS withholding tables. Withheld amounts and FICA taxes are deposited with the Treasury on a schedule tied to your total liability.14Internal Revenue Service. Topic No. 753, Form W-4, Employees Withholding Certificate
New Returns and Deadlines
An EIN brings a filing calendar that a Schedule C sole proprietor never sees. If you have employees, you file Form 941 quarterly to report withheld income tax and FICA.15Internal Revenue Service. About Form 941, Employer’s Quarterly Federal Tax Return You file Form 940 annually for FUTA.16Internal Revenue Service. About Form 940, Employer’s Annual Federal Unemployment (FUTA) Tax Return These sit on top of your business income return: Form 1120, 1120-S, 1065, or Schedule C, depending on entity type.
If you pay independent contractors, your EIN identifies you as the payer on any Form 1099-NEC you file. Starting in 2026, the filing threshold is $2,000 or more per contractor per year, up from $600 for payments made before 2026.17Internal Revenue Service. 2026 Publication 109918Internal Revenue Service. Reporting Payments to Independent Contractors
Penalties Worth Knowing About
The penalties attached to EIN-reported filings are aggressive and apply independently of each other.
Late Payroll Tax Deposits
Deposits must arrive on time, and the penalty escalates:
- 1 to 5 days late: 2% of the unpaid deposit
- 6 to 15 days late: 5%
- More than 15 days late: 10%
- More than 10 days after an IRS notice demanding payment: 15%
The tiers are not cumulative. A deposit 20 days late incurs 10%, not 2% plus 5% plus 10%.19Internal Revenue Service. Failure to Deposit Penalty
Late or Missing Information Returns
For returns due in 2026:
- Up to 30 days late: $60 per form
- 31 days late through August 1: $130 per form
- After August 1 or not filed: $340 per form
- Intentional disregard: $680 per form, no annual maximum
Small businesses with gross receipts of $5 million or less have lower annual caps, but the per-form amounts are the same. The penalty applies separately to the IRS copy and the recipient copy, so a single missed 1099 can generate two charges.20Internal Revenue Service. 20.1.7 Information Return Penalties
The Trust Fund Recovery Penalty
This is the one owners underestimate. Taxes withheld from employee paychecks are held “in trust” for the government. If they aren’t turned over, the IRS can assess a penalty equal to 100% of the unpaid trust fund taxes against any “responsible person” who willfully failed to pay.21Office of the Law Revision Counsel. 26 USC 6672 – Failure to Collect and Pay Over Tax, or Attempt to Evade or Defeat Tax That person is often the owner but can include a bookkeeper, CFO, or anyone with authority over company finances. The penalty pierces the corporate veil and is collected personally, which is why payroll deposits are never a good place to fall behind.
When a Structural Change Requires a New EIN
Your EIN stays with the entity it was issued to, but certain structural changes trigger a new one. Sole proprietors need a new EIN when incorporating, taking on a partner, going through bankruptcy, or buying an existing business to run as a sole proprietorship. Corporations need one when they receive a new state charter, become or stop being a subsidiary, convert to a partnership or sole proprietorship, or form a new corporation through a statutory merger; a corporation that simply declares bankruptcy or survives a merger keeps its existing EIN. Partnerships need a new EIN when incorporating, being taken over by one partner as a sole proprietorship, or ending one partnership and starting another; bankruptcy alone doesn’t require a new number.22Internal Revenue Service. Do You Need a New Employer Identification Number?
The through-line across all of this: the EIN is the tag, not the tax. What you owe, what you file, and when you file it depend on the entity you chose and the people you pay. Change either of those, and the tax picture changes with it.