ITR Filing 2026: These 9 Mistakes Can Delay Your Refund and Even Trigger an Income Tax Notice

By Siddhi Jain | May 6, 2026, 21:18 IST

Filing an Income Tax Return (ITR) has become much simpler in recent years, thanks to digital platforms and pre-filled forms. However, tax experts warn that even a small mistake while filing returns can create major problems later. From delayed refunds and tax notices to penalties and legal complications, simple errors can turn the process into a stressful experience.

Many taxpayers make mistakes in a hurry — some choose the wrong ITR form, while others fail to disclose complete income details. With the Income Tax Department now using advanced data-matching systems, incorrect information can quickly attract scrutiny.

Here are the 9 most common ITR filing mistakes taxpayers should avoid while filing returns for Financial Year 2025-26 and Assessment Year 2026-27.

1. Choosing the Wrong ITR Form

One of the most common and serious mistakes is selecting the incorrect ITR form.

Different categories of taxpayers are required to use different forms based on their source of income.

Common ITR Forms Explained

ITR-1: For salaried individuals with income from salary and one house property
ITR-2: For individuals or Hindu Undivided Families (HUFs) without business income
ITR-3: For taxpayers earning income from business or profession
ITR-4: For taxpayers opting for presumptive taxation under simplified income schemes

The presumptive taxation scheme is designed mainly for small businesses and professionals. Under this system, taxpayers are not required to maintain detailed accounting records because the government assumes a fixed percentage of income as profit for taxation purposes.

Experts say filing the wrong form may lead to defective return notices from the Income Tax Department and could delay processing.

2. Forgetting to E-Verify the Return

Many taxpayers believe their work is complete once the ITR is submitted online. However, filing alone is not enough.

After submitting the return, taxpayers must complete e-verification within 30 days using:

Aadhaar OTP
Net banking
Electronic Verification Code (EVC)

Without verification, the Income Tax Department treats the return as incomplete and invalid.

3. Errors in Personal Details Can Create Big Problems

Even small mistakes in personal information can lead to major complications.

Taxpayers should carefully check:

Name spelling
PAN number
Date of birth
Mobile number
Email ID
Bank account details
Assessment Year selection

Incorrect bank information may delay refunds, while selecting the wrong assessment year can create tax mismatches or double taxation issues.

4. Choosing the Wrong Tax Regime

Taxpayers now have the option to choose between the old tax regime and the new tax regime.

Many individuals select a regime without properly calculating which option is more beneficial for their income structure.

Experts recommend comparing:

Available deductions
Exemptions
Tax slabs
Investment benefits

before making a final choice.

A wrong selection could result in unnecessary tax outgo and reduced savings.

5. Not Reporting All Sources of Income

Another major mistake is hiding or forgetting certain income sources.

Taxpayers must disclose all earnings, including:

Salary income
Savings account interest
Rental income
Capital gains
Mutual fund earnings
Dividend income
Freelance income

Even tax-free income should be properly reported wherever applicable.

The Income Tax Department now cross-checks financial data through multiple sources, and undisclosed income can trigger notices or scrutiny.

6. Ignoring Form 26AS and AIS Reconciliation

Before filing ITR, taxpayers should carefully verify Form 26AS and the Annual Information Statement (AIS).

These documents contain details about:

TDS deductions
TCS entries
Tax payments
High-value financial transactions

If the information mentioned in the ITR does not match these records, it may result in:

Tax demand notices
Refund delays
Return processing issues

Experts advise reconciling all data before submission.

7. Mistakes After Changing Jobs

Taxpayers who changed jobs during the financial year often make reporting mistakes.

If an individual worked for two or more employers in the same financial year, they should collect Form 16 from every employer.

Failure to include income from all employers can lead to incorrect income reporting and additional tax liability later.

8. Forgetting Advance Tax or Exemptions

Many taxpayers forget to pay advance tax on time, especially if they have income beyond salary.

Late payment of advance tax may attract interest and penalties of up to 1 percent per month under tax rules.

At the same time, many taxpayers fail to claim eligible exemptions and deductions such as:

Section 54
Section 54EC
Section 54F

These exemptions are particularly important for taxpayers dealing with property sales or capital gains investments.

9. Ignoring Income Tax Notices

Experts strongly advise taxpayers not to ignore notices received from the Income Tax Department.

Notices may be issued for several reasons, including:

Mismatch in income details
Incorrect deductions
Non-disclosure of transactions
Defective returns

Failure to respond within the specified deadline may result in penalties, legal action, or further scrutiny.

Important ITR Filing Deadlines for AY 2026-27

Taxpayers should also remember the official filing deadlines for Financial Year 2025-26:

For General Taxpayers

Last date to file ITR: July 31, 2026

For ITR-3 and ITR-4 Filers

Last date to file ITR: August 31, 2026

Missing the deadline may attract penalties, interest charges, and delayed refunds.

Why Careful ITR Filing Matters More Than Ever

With the Income Tax Department increasingly relying on AI-based verification systems, data analytics, and automated matching tools, even minor mistakes are easier to detect now.

Experts say taxpayers should avoid rushing through the filing process and instead carefully verify every detail before submission.

A properly filed and verified ITR not only helps avoid notices and penalties but also improves financial credibility for loans, visa applications, and future financial transactions.