Per IRS Instructions for Form 990 Return of Organization Exempt From Income Tax, on page 6:

E. When, Where, and How To File

File Form 990 by the 15th day of the 5th month after the organization's accounting period ends (May 15th for a calendar-year filer). If the due date falls on a Saturday, Sunday, or legal holiday, file on the next business day. A business day is any day that isn't a Saturday, Sunday, or legal holiday.

If the organization is liquidated, dissolved, or terminated, file the return by the 15th day of the 5th month after liquidation, dissolution, or termination.

If the return isn't filed by the due date (including any extension granted), provide a reasonable cause explanation, giving the reasons for not filing on time.

F. Extension of Time To File

Use Form 8868, Application for Automatic Extension of Time To File an Exempt Organization Return, to request an automatic extension of time to file.

To complete Form 8868 Application for Automatic Extension of Time To File an Exempt Organization Return to file an extension for Form 990 Return of Organization Exempt From Income Tax return in the TaxAct program:

1. From within your TaxAct return (Online or Desktop), click Filing to expand, then click File Extension. On smaller devices, click in the upper left-hand corner, then click Filing.
2. The program will proceed with the interview questions for you to enter or review the appropriate information.

Note that any link in the information above is updated each year automatically and will take you to the most recent version of the document at the time it is accessed.