Partnerships and S Corps: What to Know Before the March 15 Deadline

March 6, 2026

By: Kevin Gehrmann

Partner, Tax

Key Takeaways

March 15 is the federal filing deadline for partnerships (Form 1065) and S corporations (Form 1120-S) — and the same date NJ PTET elections must be made for the 2025 tax year. For NY PTET, taxpayers can elect for the 2026 tax year on 3/15/2026.
NJ BAIT and NY PTET elections allow pass-through entities to pay state income tax at the entity level, creating a federal deduction that sidesteps the individual SALT cap.
With the SALT cap now raised to $40,000 under the OBBBA, the value of PTE elections should be reassessed — the math has changed for many owners.
Failing to act by March 15 can mean losing the ability to make a NJ PTET election for the entire 2025 tax year, and the 2026 tax year for NY PTET
Bottom Line: If you own a partnership or S corporation operating in New Jersey or New York, March 15 is not just a filing deadline — it’s a planning deadline.

March 15 tends to sneak up on business owners. It doesn’t get the same attention as April 15, but for partners and S corporation shareholders, it carries just as much weight. Federal returns are due. NY PTET elections must be made. And the decisions you make — or don’t make — in the next few weeks will directly affect your 2025 and 2026 tax position.

Here’s what you need to know.

The March 15 Federal Deadline: What’s Due

Partnerships filing Form 1065 and S corporations filing Form 1120-S both face a March 15 federal deadline for calendar-year filers. This is the date by which the entity must either file its return or request a six-month extension using Form 7004, pushing the deadline to September 15.

A few important notes:

Filing an extension only extends the time to file — not the time to pay. If the entity owes tax, estimated payments should already be in place. Late payment can trigger interest and penalties regardless of whether an extension is filed.

K-1s are typically issued to partners and shareholders after the entity return is prepared, which means individual owner returns often can’t be finalized until the entity return is complete. The March 15 deadline sets the entire downstream timeline in motion.

NY PTET: The March 15 Election Deadline You Cannot Miss

New York’s Pass-Through Entity Tax allows eligible partnerships and S corporations to elect to pay New York State income tax at the entity level. Because the tax is paid by the business, it is fully deductible as a business expense on the federal return — bypassing the individual SALT deduction cap entirely.

Here’s what makes the NY PTET election uniquely time-sensitive: the election for the current tax year must be made by March 15. A proposal to extend this deadline to September 15 was considered but ultimately excluded from New York’s final FY2026 budget. March 15 remains the hard deadline.

If you miss the March 15 window, you cannot make the NY PTET election for the 2026 tax year. That opportunity is gone until 2027.

For NJ and NY business owners with significant state tax liability, this is a decision that needs to happen now — not after the return is filed.

NJ BAIT: New Jersey’s Parallel Workaround

New Jersey’s Business Alternative Income Tax operates similarly to NY PTET. Eligible pass-through entities — partnerships, S corporations, and LLCs taxed as partnerships — can elect to pay New Jersey income tax at the entity level. The entity-level payment is deductible federally, and owners receive a New Jersey credit to prevent double taxation.

Unlike NY PTET, the NJ BAIT election is made annually on the New Jersey PTE-100 return and does not carry the same strict election deadline as New York. The 2025 NJ PTE election can be made by March 15,2026. However, estimated payments and timing still matter, and owners should be coordinating with their advisors well before the filing deadline to determine whether electing in is advantageous for 2025.

Does the New $40K SALT Cap Change the Calculation?

Yes — and this is where the planning gets nuanced.

Under the OBBBA, the individual SALT deduction cap has been raised from $10,000 to $40,000 for tax years 2025 through 2029, with a phaseout beginning at $500,000 in modified AGI.

For owners whose combined state income and property taxes fall under $40,000, and whose MAGI is below the phaseout threshold, the individual SALT deduction may now cover most or all of their state tax exposure. In those cases, the urgency of electing into a PTE regime is lower than it was under the old $10,000 cap.

For owners above the $500,000 MAGI threshold — where the individual SALT deduction phases out — NJ BAIT and NY PTET remain highly effective tools for capturing federal deductions that would otherwise be unavailable.

The right answer depends on each owner’s income level, the entity’s state tax liability, and how those interact with the new SALT cap. This is not a one-size-fits-all calculation.

What Partnerships and S Corp Owners Should Do Right Now

With March 15 approaching, there are a few concrete actions to take:

Confirm your filing or extension plan. Your tax advisor should already be working on your Form 1065 or 1120-S. If you haven’t connected recently, do so now. Know whether you’re filing by March 15 or extending, and make sure estimated payments are current.
Make the 2026 NY PTET election decision before March 15. This cannot wait. If your entity will have New York-source income in 2026 and you haven’t discussed the PTET election with your advisor, that conversation needs to happen this week.
Revisit NJ BAIT in light of the new SALT cap. For NJ clients, model out whether electing into BAIT still produces a net benefit given the raised individual SALT deduction. For owners with MAGI above $500,000, the answer is likely still yes.
Get K-1 information to your accountant. Partners and shareholders who delay providing financial information push the entire return timeline back, which can create downstream problems for individual returns due April 15.

The Bottom Line

March 15 is a hard stop. For partnerships and S corporations, it’s the federal filing deadline, the NY PTET election deadline, and the starting gun for individual owner returns. Missing it — or making the wrong call on PTE elections — has real tax consequences.

If you’re not sure where you stand heading into the deadline, our tax team is here to help. We work with partnerships, S corporations, and their owners across New Jersey and New York to navigate compliance, evaluate PTE elections, and build strategies that hold up year after year. Contact a Wiss advisor today.