New Mexico’s filing dates track the federal calendar — including the March pass-through deadline, unusual among the states — and its corporate tax was flattened for 2025. The state’s gross receipts tax is a major ongoing compliance obligation.
New Mexico Tax Deadlines at a Glance (2026)
Entity Type | Return Due | Extended Due Date |
|---|---|---|
Individuals (PIT-1) | April 15, 2026 | October 15, 2026 |
C Corporations (CIT-1) | April 15, 2026 | October 15, 2026 |
S Corporations (Form PTE) | March 16, 2026 | September 15, 2026 |
Partnerships (Form PTE) | March 16, 2026 | September 15, 2026 |
New Mexico is one of the states that genuinely follows the federal March pass-through deadline: Form PTE for S corporations and partnerships is due on the federal due date, March 16, 2026 (March 15 is a Sunday), extending to September 15. Individuals and C corporations file by April 15 with a federal-based automatic extension to October 15.
Corporate Tax Is Now Flat 5.9%
A 2025 change: New Mexico’s corporate income tax is now a flat 5.9% — HB 252 repealed the lower 4.8% tier effective January 1, 2025, so the old “graduated 4.8% / 5.9%” description is outdated. The individual income tax remains graduated across six brackets from 1.5% to a 5.9% top rate, restructured for 2025 by the same legislation.
Elective PTET and Gross Receipts Tax
New Mexico’s elective pass-through entity tax lets entities pay at the top individual rate (5.9%) for SALT-cap relief. Separately — and unavoidably for most businesses — New Mexico’s Gross Receipts Tax (GRT) functions as its sales tax: the state rate is 4.875% (roughly 5% to 8.9% combined with local rates), reported monthly, quarterly, or semi-annually and due the 25th of the month following the period. GRT compliance is a core part of any New Mexico engagement.
Estimates, Extensions, and Penalties
Individual estimated payments are due April 15, June 15, September 15, 2026, and January 15, 2027. A federal extension automatically extends the New Mexico return; an extension covers filing only, not payment. The late-filing/late-payment penalty is 2% per month (maximum 20%), plus interest at the IRS underpayment rate.
CPA Action Steps
File Form PTE by March 16 — New Mexico does follow the federal pass-through date
Apply the flat 5.9% corporate rate for 2025 (the 4.8% tier is gone)
Keep gross receipts tax filings on the 25th-of-month schedule
Consider the 5.9% PTET election for SALT-cap relief
Verify current rates and dates against the New Mexico Taxation and Revenue Department (tax.newmexico.gov) before filing.