Estimated Tax — Instruction 1120-S — Instructions for Form

Generally, the corporation must make installment payments of estimated tax for the following taxes if the total of these taxes is $500 or more. (a) The tax on built-in gains. (b) The excess net passive income tax. (c) The investment credit recapture tax, each discussed later.

The amount of estimated tax required to be paid annually is the smaller of (a) the total of the above taxes shown on the return for the tax year (or if no return is filed, the total of these taxes for the year) or (b) the sum of (i) the investment credit recapture tax and the built-in gains tax shown on the return for the tax year (or if no return is filed, the total of these taxes for the tax year) and (ii) any excess net passive income tax shown on the corporation’s return for the preceding tax year. If the preceding tax year was less than 12 months, the estimated tax must be determined under (a).

The estimated tax is generally payable in four equal installments. However, the corporation may be able to lower the amount of one or more installments by using the annualized

income installment method or adjusted seasonal installment method under section 6655(e).

For a calendar year corporation, the payments are due for 2026 by April 15, June 15, September 15, and December 15. For a fiscal year corporation, they are due by the 15th day of the 4th, 6th, 9th, and 12th months of the year. If any date falls on a Saturday, Sunday, or legal holiday, the installment is due on the next day that isn’t a Saturday, Sunday, or legal holiday.

The corporation must make the payments using electronic funds transfers as described earlier.

For information on penalties that may apply if the corporation fails to make required payments, see the Instructions for Form 2220.