S Corp Tax Filing Deadline 2025. Electing s corp status for an existing company. The deadline for filing form 1120s is march 17, 2025, since march 15 falls on a weekend.

If you are a sole proprietor, a partnership, or an s corporation, you can view your tax information on record with the irs and do more with a business tax account. It is also the partnership tax deadline to file your return ( form 1065 ).