Although the April 15 IRS tax deadline has passed, taxpayers in Delaware, Iowa, Virginia, Louisiana, and South Carolina are still on the hook for their state returns — or have just received extra time.
It has been a tumultuous tax season. The 2025 Trump tax bill not only overhauled federal rules but also prompted state lawmakers to wrestle with whether to adopt federal tax code changes.
While these updates may have yielded new tax savings for some taxpayers who live in states that adopted them, the new rules also led to state refund delays, even leading one state tax agency to move its filing deadline as far as October.
So, when is your state tax return due? If you live in one of these states, here's who needs to file by April 30, which taxpayers have more time, and state tax policy to watch as we move further into 2026.
April 30 deadlines: Delaware and Iowa state taxes are due
The two states with income taxes due by April 30, 2026, are Delaware and Iowa. Even though the federal deadline passed on April 15, residents in these states have until the end of the month to finalize their state returns.
"The Iowa Department of Revenue is once again reminding Iowans of the many resources available that can assist taxpayers with filing their tax return," noted Iowa's DOR in a press release, "[State] income tax returns are due on April 30."
What is due by April 30, 2026?
- Individual state tax returns. Both final filings and any tax payments owed.
- Estimated state tax payments. The first quarter installment for the 2026 tax year (in Iowa only; Delaware's estimated payments were due April 15).
Federal estimated tax payments were due April 15, 2026.
Virginia and Louisiana state income tax returns are due May 2026
Taxpayers in Virginia and Louisiana have even more breathing room, with state tax deadlines stretching into May 2026.
- Virginia residents have until May 1, 2026, to file state income tax returns.
- Louisiana taxpayers have until May 15, 2026, to submit their state returns.
What is due in May 2026?
- Individual state income tax returns. Final filings and payments for both Virginia and Louisiana.
- State business tangible property tax returns. This includes returns for specific jurisdictions in Virginia, like Arlington County.
South Carolina taxpayers have a special extended tax deadline for the 2026 tax season that extends beyond May (more on that later).
2026 mail rules for filing state tax returns
You may file by mail or electronically, but most state tax agencies recommend the latter. Not only does e-filing typically yield quicker processing than for paper returns, but it also bypasses the risks associated with the new USPS postmark rule.
Under this new policy, physically mailed returns are often not postmarked until they reach a regional processing center. If you mail your return on the deadline date, your state income filing might not be stamped until the following day, potentially leading to late-filing penalties.
Note on state tax extensions: If you can't file on time, you should file for a state tax extension (which usually pushes your tax filing due date until October 15 or later). This differs from the federal extension, which should have been requested by April 15.
But remember, an extension to a file is not an extension to pay. Be sure to estimate and pay your tax liability by the state deadline to avoid any late-payment interest and penalties.
New tax law changes for states in 2026
As mentioned, several states adopted federal changes from the 2025 Trump tax bill, which are now impacting the 2026 state tax season.
Of the states with April 30 deadlines (or later), conformity varies:
- Delaware: partially conformed, decoupling from business expense provisions and some individual deductions like "no tax on tips."
- Iowa: rolling conformity, adopting most major federal tax changes automatically.
- Louisiana: partially conformed, decoupling from certain business expense deductions.
- Virginia: partially conformed, including the temporary adoption of an increased standard deduction.
What does this mean for you? In many cases, the Trump tax law changes might lend higher tax savings on some state returns (e.g., if you were a worker who qualified for the federal overtime tax deduction).
However, in states that did not conform to these individual tax breaks — like South Carolina — you may be required to "add back" those deductions on your state return, even if you claimed them on your federal filing.
South Carolina 2026 tax extension deadline: October 15
South Carolina state lawmakers debated whether to conform or decouple from the Trump tax law changes for most of the 2026 tax season. As a result, the processing of state income returns for early filers was delayed, and the state return deadline was eventually extended.
"We are automatically extending the tax filing due date for all 2025 South Carolina Individual Income Tax returns to October 15, 2026," the South Carolina Department of Revenue acknowledged in a recent release. "This extension applies only to the deadline to file your return, not to pay what you owe."
The new Trump tax law changes were enacted federally after many states had already concluded their summer legislative sessions. As such, more states may decouple or conform to federal tax policy when legislatures meet for their regular sessions in the next few months. What comes out of those sessions may ultimately impact how much you owe in 2026 state income taxes.
Stay tuned for updates.
