The IRS charges nothing to file Form 1120-S itself. The real cost to file Form 1120-S is preparation: roughly $150 to $300 if you use business tax software, and about $800 to $2,500 or more if you hire a CPA or enrolled agent. Most single-shareholder S corporations with clean books land between $800 and $1,500 for professional preparation. Complex returns run higher, sometimes $2,000 to $4,000 or more.
What a CPA or Enrolled Agent Charges
Hiring a professional is the common route, and it usually makes sense. Form 1120-S requires balance sheet reconciliation, correct allocation of income and deductions to each owner, and a Schedule K-1 for every shareholder. Current estimates put standard preparation for S corporations and other pass-through entities at $1,000 to $2,000, with complex returns running $2,000 to $4,000 or higher.
A simple, single-shareholder S corporation with organized bookkeeping and one state of operation typically falls at the lower end, around $800 to $1,200. Simple disappears fast once you add inventory, meaningful fixed assets, or revenue from multiple states.
Preparers price the work two ways. Flat fees apply when records are organized and the scope is predictable. Hourly billing kicks in when the CPA has to clean up bookkeeping, hunt down missing documents, or provide planning beyond the return. Hourly CPA rates generally run $150 to $500, with geography the biggest variable. A standard flat-fee engagement usually covers the federal 1120-S, a Schedule K-1 for each shareholder, and electronic filing.
Return Preparation Versus Tax Planning
Paying someone to complete last year’s return is a different service from paying someone to structure the current year to reduce taxes. Return preparation is backward-looking. Planning is forward-looking and costs more because it is ongoing. CPAs who offer year-round advisory work often charge monthly retainers of $1,000 to $6,000 depending on business complexity. That is a separate cost from annual 1120-S preparation, though some firms bundle them. For many S corporation owners, the planning is where the tax savings actually come from, particularly around reasonable compensation and the timing of distributions.
Filing Form 1120-S Yourself With Software
Self-filing is the cheapest path but not the right fit for everyone. Personal tax software does not handle business entity returns. You need the business or corporate edition, which typically costs $150 to $300 for the federal return, plus $50 to $65 for each state filing.
This approach demands real comfort with business accounting, including balance sheet reconciliation and shareholder basis tracking. Basis is where self-preparers most often go wrong. Inaccurate basis records can cause distributions to be mischaracterized, which creates unexpected taxable gain when a shareholder pulls money out. 1Internal Revenue Service. S Corporation Stock and Debt Basis The IRS expects shareholders to be able to demonstrate adequate stock basis for any non-dividend distribution to be treated as tax-free.
Realistically, DIY software works for S corporations with low transaction volume, one shareholder, one state, and no complicated assets or liabilities. Add a second shareholder, multi-state operations, or depreciation, and the error risk starts outweighing the savings. Some vendors offer an audit defense add-on for around $45 to $60 that provides professional representation if the IRS examines the return.
What Pushes the Price Higher
The bill is a function of time and complexity. Knowing what drives it up helps with budgeting, and some of it is within your control.
- Revenue volume. Higher gross receipts mean more transactions to categorize and reconcile. A business doing $5 million generates far more line items than one doing $150,000, and preparer time scales with that.
- Balance sheet complexity. Significant inventory, large fixed assets, or complex debt require additional forms. Depreciation alone may require Form 4562, which adds time and cost.2Internal Revenue Service. About Form 4562, Depreciation and Amortization (Including Information on Listed Property)
- Number of shareholders. Each owner needs a separate Schedule K-1 with correctly allocated income, deductions, and credits. Most CPAs charge a per-K-1 fee on top of the base rate.
- Multi-state operations. Each state where the S corporation has nexus requires its own return, its own allocation rules, and its own preparation fee.
- Bookkeeping condition. A CPA who receives a box of receipts instead of a clean general ledger will bill cleanup work at their hourly rate. This can easily add hundreds or thousands of dollars and is the single most controllable cost in the process.
What Filing Late Costs
Missing the deadline turns a free filing into an expensive one. The federal penalty is $255 per shareholder for each month or partial month the return is late, up to 12 months. 3Office of the Law Revision Counsel. 26 USC 6699 – Failure to File S Corporation Return The amount is inflation-adjusted annually from a statutory base of $195. A four-shareholder S corporation that files six months late owes $6,120. The penalty falls on the corporation, not the individual shareholders.
Form 1120-S is due on the 15th day of the third month after the tax year ends. 4Internal Revenue Service. Starting or Ending a Business 3 For calendar-year S corporations, that is March 15. Filing Form 7004 before the deadline gives you an automatic six-month extension to September 15. 5Internal Revenue Service. About Form 7004, Application for Automatic Extension of Time To File Certain Business Income Tax, Information, and Other Returns The extension is free. It extends time to file, not time to pay any tax the corporation itself owes.
Two relief paths exist. The IRS offers first-time penalty abatement for S corporation late-filing penalties if the company has a clean compliance history for the prior three years. 6Internal Revenue Service. Administrative Penalty Relief The penalty also does not apply where the corporation shows reasonable cause, meaning circumstances beyond your control prevented timely filing despite ordinary business care.
Other Annual Costs That Come With an S Corporation
The 1120-S preparation fee is one line in a larger annual compliance budget. Several other costs come attached to the structure.
State Returns and Franchise Taxes
Most states require a separate S corporation return, and many impose entity-level taxes or fees. State filing fees typically run $50 to $150 per state for simple returns, on top of the CPA’s preparation fee for each state. Multi-state operations can push aggregate state compliance into the same range as the federal return.
Most states also require an annual report or franchise tax to keep the corporation in good standing. These fees vary widely, from under $50 in some states to $800 in states with minimum franchise taxes. Missing them can lead to administrative dissolution.
Payroll for Shareholder-Employees
The IRS requires any S corporation shareholder-employee who provides more than minor services to receive reasonable compensation as W-2 wages, not just distributions. 7Internal Revenue Service. S Corporation Employees, Shareholders and Corporate Officers That means running payroll. A payroll service typically costs $40 to $100 per month plus per-employee fees. The corporation also files quarterly Form 941 and annual Form 940, each of which is either extra preparer fees or extra hours if you handle it yourself. 8Internal Revenue Service. About Form 941, Employer’s Quarterly Federal Tax Return
Shareholder Estimated Tax Payments
Because the S corporation is a pass-through, shareholders pay the tax on their allocated share of income personally. Nothing is withheld from those allocations. Shareholders who expect to owe $1,000 or more in federal tax for the year must make quarterly estimated payments using Form 1040-ES, due in April, June, September, and January. Missing them triggers an underpayment penalty that works like interest on the shortfall. This is a shareholder-level cost rather than a corporate one, and it catches many new owners off guard.
Electronic Filing
S corporations that file 10 or more returns of any type during the calendar year, counting income tax, employment tax, and information returns, must file Form 1120-S electronically. 9Internal Revenue Service. Instructions for Form 1120-S Almost every S corporation with employees hits that threshold once you add up quarterly 941s, the annual 940, W-2s, and the 1120-S. E-filing itself is free through a CPA or tax software. Corporations that cannot meet the requirement can request a waiver from the IRS.