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AB The Tax Expert

S corp tax preparation

S corp tax preparation: Form 1120-S and K-1s, from clean books.

Your S corporation return, prepared by the team that can also keep the books behind it. Base price $1,200 for the federal Form 1120-S with shareholder K-1s, published up front. S corporations in California and every other state — handled online.

What’s included

What S corp tax preparation covers.

Form 1120-S, prepared and e-filed

The federal S corporation return, including the balance sheet (Schedule L), the book-to-tax reconciliation (Schedule M-1) and the equity roll-forward (Schedule M-2) where required.

Schedule K-1 for every shareholder

Each owner’s share of income, deductions, credits and distributions, delivered in time to file their personal return.

Officer compensation review

The IRS requires shareholder-employees to be paid reasonable wages before taking distributions. We review what was paid against what the business did, and flag gaps before the return is filed.

Shareholder basis tracking

Basis determines whether distributions are tax-free and whether losses can be deducted. We track it each year so your personal Form 7203 is supportable.

State S corporation return

Prepared alongside the federal return for the state where the corporation is registered — California Form 100S, or the equivalent elsewhere — and quoted with it.

Extension when you need one

If the books aren’t ready by March, we file Form 7004 for the automatic six-month extension so the return is right rather than rushed.

Deadlines and penalties

S corp tax deadlines you can’t afford to miss.

March 15 (or the next business day)

Calendar-year Form 1120-S is due on the 15th day of the third month after year end. Tax-year 2025 returns were due March 16, 2026; tax-year 2026 returns are due March 15, 2027. Full deadline and extension guide →

Six-month extension to September 15

Form 7004 extends the filing deadline, not the K-1 timing your shareholders are waiting on for their own returns — so we plan the books around it.

Late-filing penalty: per shareholder, per month

For returns due after December 31, 2025 the penalty is $255 per shareholder for each month or part of a month the return is late, up to 12 months — even when no tax is due. A two-owner S corp that files six months late owes $3,060 before interest.

K-1 furnishing penalty

Failing to furnish a correct K-1 to a shareholder on time carries its own penalty per statement, separate from the late-return penalty.

California: 1.5% tax and $800 minimum

California S corporations pay 1.5% of net income with an $800 minimum franchise tax (waived for the first year of a new corporation) on Form 100S, due the same day as the federal return.

How it works

How we prepare your S corp return.

1. Scope and quote

We confirm the entity, the state, the number of shareholders and the state of the books, then confirm the price from the $1,200 base before any work begins.

2. Books first

An 1120-S is prepared from a reconciled balance sheet, not a bank download. If the books are behind, catch-up bookkeeping comes first and is quoted separately.

3. Documents

Year-end financials, payroll reports, prior-year return, shareholder details and the items on our checklist below, uploaded to your secure portal.

4. Prepare

Officer pay, distributions, basis, depreciation and state adjustments are worked through, with questions batched rather than sent one at a time.

5. Review together

You see the return and each K-1 before anything is filed, with the changes from last year explained.

6. E-file and deliver

Federal and state returns e-filed, acceptance confirmed, and K-1s delivered to each shareholder.

What we’ll need

S corp tax return checklist.

Year-end financial statements

Profit & loss and balance sheet for the year, reconciled to the bank and credit card statements.

Payroll reports and W-2s

Officer and employee wages for the year, including W-2s and Forms 941/940 or your payroll provider’s annual summary.

Prior-year 1120-S and K-1s

Last year’s return carries forward basis, depreciation and any suspended items.

Shareholder details

Names, addresses, ownership percentages and any changes in ownership during the year, plus distributions paid to each owner.

Asset purchases, loans and health insurance

Fixed assets bought or sold, loan statements, and shareholder health insurance premiums (which belong on the W-2).

State registrations

Where the corporation is registered, where it has employees or property, and any state estimated payments already made.

Pricing

S corp tax preparation cost.

$1,200 base price

The S corporation return prepared and filed, with owner K-1s. Base pricing is published on the pricing page so you know where you stand before we begin.

What can move the price

Additional states, a large number of shareholders, unreconciled books, fixed-asset schedules that need rebuilding, or a mid-year ownership change. We confirm the full scope and price before work begins — not after.

Owner returns

Your K-1 flows to your personal return. Personal tax preparation starts at $300 and is quoted alongside the business return when we prepare both.

Books and taxes together

Clients on a monthly bookkeeping plan arrive at tax season with a reconciled balance sheet already done, which is what keeps an S corp return at the base price.

Related

Other entity returns and related help.

All business returns

Schedule C, partnership, S corporation and C corporation returns, prepared from clean books. Business tax preparation →

Thinking about electing S corp status?

Form 2553 is due within 2 months and 15 days of the start of the tax year it should apply to; late elections can often be fixed. We’ll walk through whether it fits before you file it. Ask us →

Behind on filing?

Unfiled 1120-S years accrue the per-shareholder penalty every month. We rebuild the books and file the missing years together. IRS resolution →

Books not ready?

The return starts with reconciled books. Catch-up bookkeeping →

Common questions

How much does S corp tax preparation cost?

Our base price is $1,200 for the Form 1120-S with shareholder K-1s. Additional states, many shareholders or books that need cleanup can add to it, and we confirm the full price before starting.

When is the S corp tax return due?

March 15 for calendar-year corporations, or the next business day when that falls on a weekend. Form 7004 extends it six months to September 15.

What is the penalty for filing Form 1120-S late?

For returns due after December 31, 2025, $255 per shareholder for each month or part of a month the return is late, for up to 12 months, even if no tax is owed.

Do I have to pay myself a salary from my S corp?

If you work in the business, the IRS expects reasonable compensation through payroll before distributions. We review officer pay as part of every S corp return.

Can you prepare the return if my books are a mess?

Yes, but the books come first. We scope catch-up bookkeeping separately, then prepare the 1120-S from the reconciled result.

Do you handle California S corporations?

Yes — Form 100S, the 1.5% California tax and the $800 minimum are part of the state return, and we prepare S corp returns for businesses in other states as well.

Ready to get your S corp return done?

Answer a few questions about your corporation and we’ll confirm the scope and price.

Get Started