The corporation must pay any tax due in full no later than the due date for filing its tax return. Filing an extension will NOT extend the payment due date. The corporation can send a check or pay electronically with the Electronic Federal Tax Payment System (EFTPS). For any deposit made by EFTPS, the corporation must submit the deposit by 5PM PST the day before the deposit is due.
If the corporation expects the total tax for the year to be $500 or more, then the corporation must make installment payments of estimated tax. The installments are due by the 15th day of the 4th, 6th, 9th, and 12th months of the year, if applicable.
Interest is charged on taxes paid late even if an extension of time to file is accepted. Interest is also charged on penalties imposed for failure to file or understating transactions and tax. A corporation that does not file its tax return by the due date, including extensions, may be penalized 5 of the unpaid tax for each month, up to a maximum of 25 of the unpaid tax. A corporation that does not pay the tax when due may be penalized 0.5 of the unpaid tax for each month the tax is not paid, up to a max of 25 of the unpaid tax.