S-Corp Compliance: Payroll, Filings, and Ongoing Requirements (2026)
The S-Corp election saves money, but it comes with obligations. This page lays out every requirement, every deadline, and every cost so there are no surprises.
Monthly Requirements
Run payroll
Process your own W-2 salary through a payroll service. Most S-Corp owners run monthly payroll. Some run biweekly. Your payroll service handles the calculations, tax withholding, and direct deposit.
Deposit payroll taxes
Federal income tax withholding, employee and employer FICA (Social Security + Medicare). Your payroll service deposits these automatically. For most single-owner S-Corps, deposits are made monthly or semi-weekly depending on the deposit schedule assigned by the IRS.
State payroll tax deposits
Most states require payroll tax deposits on the same schedule as federal. Your payroll service handles this too, but you need state payroll tax accounts set up.
Maintain separate business bank account
All business income flows in, salary and distributions flow out. Do not commingle personal and business funds. This is not just good practice, it is critical for maintaining your LLC's liability protection.
Quarterly Requirements
File Form 941 (Employer's Quarterly Federal Tax Return)
30 days after quarter endReports wages paid, tips, federal income tax withheld, and employer/employee FICA. Due April 30, July 31, October 31, January 31. Your payroll service can file this automatically.
Estimated tax payments (if applicable)
4 times/yearIf you expect to owe $1,000+ in federal taxes beyond withholding, make quarterly estimated payments using Form 1040-ES. Due April 15, June 15, September 15, January 15.
State quarterly payroll tax filings
Varies by stateMost states require quarterly wage reports. Requirements vary by state. Your payroll service handles the filing.
Annual Requirements
File Form 1120-S (S-Corp tax return)
March 15The S-Corp's informational return. Reports income, deductions, credits, and each shareholder's share of income. Your CPA prepares this. Extension available to September 15.
Issue K-1 to shareholders
March 15Schedule K-1 shows each shareholder's share of S-Corp income, deductions, and credits. As a single-owner S-Corp, you issue a K-1 to yourself. This flows to your personal return.
Issue W-2 to yourself
January 31Your payroll service generates your W-2 automatically. You receive it by January 31 and use it to file your personal return.
File W-3 transmittal with SSA
January 31Transmittal form for W-2s filed with the Social Security Administration. Your payroll service handles this.
State annual report
Varies by stateMost states require an annual or biennial report. Fees range from $0 to $800. Check your state's Secretary of State website.
File personal tax return with K-1 income
April 15Your personal 1040 includes W-2 income from your salary and K-1 income from S-Corp distributions. Your CPA handles this.
Compliance Calendar
Every S-Corp deadline in one view. Mark these dates.
| Month | Deadline | What to File |
|---|---|---|
| January 31 | Hard | W-2 to yourself, W-3 to SSA, 1099s to contractors, Q4 Form 941 |
| March 15 | Hard (ext. to Sept 15) | Form 1120-S, Schedule K-1 to shareholders |
| April 15 | Hard (ext. to Oct 15) | Personal 1040 with K-1, Q1 estimated tax payment |
| April 30 | Hard | Q1 Form 941 |
| June 15 | Hard | Q2 estimated tax payment |
| July 31 | Hard | Q2 Form 941 |
| September 15 | Hard | Q3 estimated tax payment, 1120-S extension deadline |
| October 15 | Hard | Personal return extension deadline |
| October 31 | Hard | Q3 Form 941 |
| Varies | State-specific | State annual report, franchise tax |
Detailed Cost Breakdown
Every ongoing cost of maintaining an S-Corp, itemized. These are the costs you subtract from your gross tax savings to calculate net benefit.
| Item | Low End | High End | Realistic |
|---|---|---|---|
| Payroll service (Gusto, ADP Run, QBO) | $600 | $1,800 | $900 |
| CPA: Form 1120-S preparation | $500 | $1,500 | $800 |
| CPA: Payroll tax compliance review | $0 | $500 | $200 |
| Registered agent (if using a service) | $0 | $200 | $100 |
| State annual report fee | $0 | $500 | $50 |
| State franchise tax (CA, others) | $0 | $800+ | $0 |
| Bookkeeping software (QuickBooks, Xero) | $0 | $480 | $200 |
| Total annual S-Corp overhead | $1,100 | $5,780 | $2,250 |
The "Realistic" column reflects typical costs for a single-owner S-Corp using Gusto for payroll and a local CPA for tax prep, in a state without franchise tax. California residents should add $800+ for franchise tax.
What Happens If You Miss Requirements
The IRS takes payroll tax obligations very seriously. Unlike income tax, where penalties are moderate, payroll tax penalties escalate quickly and can include personal liability.
Late filing of Form 1120-S
$235 per shareholder per month (or partial month), up to 12 months. For a single-owner S-Corp, this is $235/month. Filing 6 months late: $1,410.
Failure to file or late filing of Form 941
5% of unpaid tax for each month late, up to 25% maximum. Plus failure-to-deposit penalties of 2-15% depending on how late.
Failure to deposit payroll taxes
2% if 1-5 days late, 5% if 6-15 days late, 10% if 16+ days late, 15% if not deposited within 10 days of IRS notice. These are applied to the tax amount, not wages.
Trust Fund Recovery Penalty (TFRP)
If you willfully fail to collect, account for, or deposit employment taxes, the IRS can assess a penalty equal to 100% of the unpaid trust fund taxes against you personally. This pierces corporate protections.
Late W-2 filing
$60 per form if filed within 30 days late, $120 per form if 31 days to August 1, $310 per form if after August 1 or not filed.
State penalties
Vary by state. California charges 5% of unpaid tax per month (up to 25%) plus interest. Most states follow a similar escalating penalty structure.
This is not meant to scare you. Using a payroll service and a competent CPA eliminates nearly all risk of these penalties. The service handles deposits and filings automatically. The CPA files your 1120-S on time. The penalties exist for people who try to handle it all manually and forget.
Tools That Make It Easier
Payroll
Most popular for single-owner S-Corps. Handles everything.
Established provider. Good for businesses planning to add employees.
Best if you already use QuickBooks for bookkeeping.
Accounting
Industry standard. Your CPA will likely prefer this.
Clean interface. Good alternative to QuickBooks.
Best for freelancers. Simple invoicing and expense tracking.
Tax Preparation
Find one who regularly files 1120-S returns. Ask for references.
DIY option. Only recommended if you are tax-savvy.
All-in-one S-Corp service (formation, payroll, tax prep).