2026 Tax Day deadline April 15: 5 IRS mistakes that can delay your refund

Tax Day is coming, and many people wait until the last moment to file their taxes. If you like working close to deadlines, there are important dates to mark on your calendar and be cautious about some filing mistakes. The tax filing deadline for 2026 is April 15, which falls on a Wednesday this year, as noted by Yahoo Finance.

If you cannot file by April 15, you can request a six-month extension. Even with an extension, you should still estimate and pay any taxes owed to avoid penalties. The Internal Revenue Service reminds taxpayers that filing late without an extension may lead to fees. After noting the deadline, taxpayers should double-check their returns to avoid errors.

The 2026 tax season has started, and filing mistakes can cause delays, rejected returns, or refund problems. The IRS says even small errors like a misspelled name or wrong bank number can create big issues. These small mistakes are easy to miss, especially when you handle many tax documents. Checking details carefully can save you from correcting or re-filing later.

1. Wrong SSN details

One common mistake is entering the wrong Social Security Number (SSN). It must match exactly with your card. Other ID numbers like ITIN and EIN must also be correct on the tax return. If you don’t have an SSN but qualify, you must apply using Form SS-5. Form SS-5 can also be used to replace or correct SSN details, as noted by Kiplinger. Children or dependents aged 12+ without SSN must apply in person.

If someone cannot get an SSN, they must use an ITIN issued by the IRS. ITIN is a 9-digit number used for federal tax purposes. To apply for ITIN, taxpayers must submit Form W-7. Businesses and employers also need an EIN for tax filings.

2. Expired ITIN problem

Another mistake is filing taxes with an expired ITIN. ITIN expires if not used for 3 straight tax years. The ITIN expires on December 31 after the third inactive year, as stated by Kiplinger. This often happens with students or people who don’t earn enough to file taxes. Filing with an expired ITIN can delay refunds or block tax credits. It may also lead to penalties, interest, or smaller refunds. However, you don’t need an ITIN to request an extension or pay estimated tax.

3. Typos and math errors

Typos and math errors are also common tax mistakes. A misspelled name must match the Social Security card. A wrong bank account number can send your refund to the wrong place. If bank details are wrong, contact the IRS to stop direct deposit. The IRS may then send your refund by mail instead. Math mistakes can delay processing. Usually, the IRS corrects math errors automatically. Taxpayers will receive a “math error notice” explaining corrections. A new law now makes these notifications mandatory.

4. Wrong filing status

Filing with wrong status, dependents, income, or credits is another mistake. If that happens, you must file an amended return using Form 1040-X, as per Kiplinger. Errors in tax credits like Earned Income Tax Credit can also cause problems. The IRS provides an Interactive Tax Assistant to help calculate credits.

5. Unsigned tax return

Unsigned tax returns are not valid. The IRS will send unsigned returns back for signature. This can also lead to delinquency penalties in some cases.

To avoid mistakes, review all tax documents before submitting. Filing electronically reduces errors because software checks math. Tax software also flags missing information. You can file for free or use Volunteer Income Tax Assistance (VITA), as cited by Kiplinger. Tax Counseling for the Elderly (TCE) is also available. Choosing direct deposit helps prevent lost refund checks. Using a certified tax preparer or reliable software helps avoid mistakes. The main message: small errors can delay refunds, so double-check everything.

FAQs

Q1. What happens if I make a mistake on my tax return?

Small mistakes can delay your refund or even cause your return to be rejected, according to the Internal Revenue Service.

Q2. Can I fix a wrong tax return after filing?

Yes, you can correct errors by filing an amended return if details like income, dependents, or credits are wrong.