How to Complete and Pay Form NYC-400: Due Dates and Penalties

Form NYC-400 is the estimated tax declaration a corporation files with the New York City Department of Finance when it expects to owe more than $1,000 in Business Corporation Tax or General Corporation Tax for the year.¹ The form breaks the annual bill into installments. The first 25% is handled on a different form or with your prior-year return; NYC-400 covers the balance, split across the remaining due dates in the year.

Who Has to File

Every corporation subject to the General Corporation Tax (Title 11, Chapter 6, Subchapter 2 of the Administrative Code) or the Business Corporation Tax (Subchapter 3-A) must file NYC-400 if its estimated tax for the year is reasonably expected to top $1,000.¹ Estimated tax means the tax your corporation expects to owe minus any credits it expects to claim. If that net figure exceeds $1,000, you file.

A corporation is doing business in the city if it employs capital, owns or leases property, or maintains an office there. Nexus can also be triggered through credit card activity (for example, 1,000 or more cardholders or merchants at NYC addresses) or by holding a partnership interest in a partnership that does business in the city.² A brand-new corporation or one that previously paid only the minimum tax can still cross the $1,000 threshold and have to file.

The First Installment Works Differently

Before you reach NYC-400, you handle the first 25% of estimated tax, and the mechanism depends on whether you’re a C corp or an S corp.

C Corporations: Form NYC-300

C corporations subject to the Business Corporation Tax file Form NYC-300 and pay a Mandatory First Installment equal to 25% of the tax from the second preceding tax year, as long as that year’s tax exceeded $1,000.³ For a calendar-year corporation filing in 2026, the second preceding year is 2024. A corporation with no second preceding tax year skips NYC-300 and begins its estimated payments on NYC-400.

S Corporations: With the Prior Year Return

S corporations and qualified Subchapter S subsidiaries subject to the General Corporation Tax pay 25% of the preceding year’s tax as a first installment, remitted with the prior year’s tax report or with the extension request for that report.¹ The preceding year’s tax has to have exceeded $1,000 for this requirement to apply.

After the 25% is paid, subtract it, along with any overpayment credit you carried forward from last year’s return, from your current estimate. The remainder is what NYC-400 divides into installments.

Installment Schedule and Due Dates

How many installments you make depends on when during the year you first meet the filing requirement. For a calendar-year corporation:¹

Requirements met before June 1: file by June 15 and pay the balance in three equal installments on June 15, September 15, and December 15.
Requirements met June 1 through August 31: file by September 15 and pay in two equal installments on September 15 and December 15.
Requirements met September 1 through November 30: file by December 15 and pay the full balance then. You can instead file a completed tax report with any remaining balance by the 15th day of the second month of the following year (February 15 for calendar-year filers).

If a due date lands on a Saturday, Sunday, or legal holiday, the deadline shifts to the next business day. Fiscal-year filers use the 6th, 9th, and 12th months of their own fiscal year in place of the calendar months above.

Filling Out the Form

NYC-400 is a single page. The information it asks for is specific.

Enter the corporation’s legal name as it appears on its state registration and its federal Employer Identification Number. The instructions emphasize that the correct EIN is what links your payment to your account.¹ Enter the beginning and ending dates of your taxable year. Calendar-year filers use January 1 through December 31.

For the tax computation, show your estimated total tax for the year under either Section 11-603 (General Corporation Tax) or Section 11-653 (Business Corporation Tax) of the Administrative Code. Start with projected tax, subtract credits you expect to claim, then subtract the 25% first installment already paid and any overpayment credit you carried forward from last year.¹ What’s left is the balance you divide into installments.

The prior-year total tax figure you need for the first installment calculation comes from your previous NYC-2 (Business Corporation Tax Return) or prior General Corporation Tax return. A transposed digit or a missed credit here can produce an underpayment notice months later.

Submitting and Paying

The Department of Finance prefers electronic filing through its e-Services portal at nyc.gov/eservices, which handles both the declaration and the payment.¹ Select the correct tax type (Business Corporation Tax or General Corporation Tax) and enter the corporation’s EIN so the payment posts to the right account.

Paper filing is available. Mail the completed form with payment to:

NYC Department of Finance
P.O. Box 3922
New York, NY 10008-3922¹

Keep your confirmation number or proof of mailing. For a mailed paper form, the postmark date is what counts toward meeting the deadline.

Changing Your Estimate Mid-Year

If your projected tax changes during the year, file a new Form NYC-400 on the next installment due date. The amended form replaces the original estimate and recalculates the remaining installments.¹ One timing rule: if you amend after the 15th day of the 9th month (September 15 for calendar-year filers), any increase in tax has to be paid with the amendment itself and cannot be deferred to a later installment.

Penalties for Underpayment

Under Section 11-676 of the Administrative Code, any shortfall is treated as an underpayment, and interest runs on the unpaid amount daily from the installment due date until the 15th day of the third month after the tax year ends (March 15 for calendar-year filers).⁴

The interest rate resets quarterly. For the first quarter of 2026, the rate on NYC business tax underpayments is 11%; for the second quarter, it is 10%.⁵ Current quarterly rates are posted at nyc.gov/finance, and 311 (212-639-9675 from outside the city) will confirm them. Form NYC-222 (Underpayment of Estimated Tax by Business and General Corporations) is the worksheet for computing whether a penalty is owed and how much.⁶

How to Avoid the Penalty

No underpayment penalty applies if your total estimated payments by each due date equal or exceed the least of several benchmarks. The two most commonly used:

Payments that equal or exceed the tax shown on your return for the preceding year, provided that year was a full 12-month taxable year and the return showed a tax liability.⁴
Payments that equal or exceed 90% of the tax ultimately shown on the current year’s return. If payments fall short of 90% but would have been sufficient at an 80% threshold, the penalty is reduced to 75% of what would otherwise apply.⁴

The Department of Finance’s General Corporation Tax page summarizes the safe harbor as payments of not less than 90% of the tax finally determined, or not less than the prior year’s tax.⁷ Corporations with uneven income can also look at annualized-income and seasonal-income exceptions on Form NYC-222.⁶

For most corporations, paying 100% of last year’s tax across the installments is the straightforward way to stay inside the safe harbor regardless of how the current year turns out.

1
NYC Department of Finance. Form NYC-400 – 2026 – Instructions
2
NYC Department of Finance. Business Corporation Tax
3
NYC.gov. Mandatory First Installment (MFI) by Business C Corporations
4
Justia Law. New York Code – Additions To Tax And Civil Penalties
5
NYC Department of Finance. Business Interest Rates
6
NYC.gov. Underpayment of Estimated Tax by Business and General Corporations (Form NYC-222)
7
NYC Department of Finance. Business General Corporation Tax – GCT