Common ITR Filing Mistakes to Avoid in AY 2026–27: Complete Guide

Filing an Income Tax Return (ITR) is an important financial and compliance responsibility. However, many taxpayers make avoidable mistakes while filing their returns. Errors such as selecting the wrong ITR form, missing income details, claiming incorrect deductions, ignoring AIS information, entering incorrect bank details, or forgetting to e-verify the return may lead to delays, notices, tax mismatches, or the need to revise the return.

For AY 2026–27, taxpayers should carefully review their income, tax details, deductions, and return information before submission. A properly prepared Income Tax Return can help ensure smoother processing and reduce the chances of avoidable compliance issues.

In this detailed guide, we explain the most common ITR filing mistakes, how to avoid income tax return errors, and the important checks to complete before submitting your ITR.

If you are filing an ITR for the first time or need a complete overview of the filing process, read our Complete Guide to ITR Filing for AY 2026–27: Everything You Need to Know.

Why Is It Important to Avoid ITR Filing Mistakes?

An Income Tax Return contains important information about your income, tax payments, deductions, exemptions, bank accounts, and other financial details.

Even a small mistake may result in:

• Delay in ITR processing
• Delay in income tax refund
• Tax credit mismatch
• Defective return communication
• Incorrect tax calculation
• Additional tax, interest, or applicable fees
• Requirement to revise or correct the return
• Follow-up communication from the Income Tax Department

The best approach is to verify every important detail before submitting the return.

1. Choosing the Wrong ITR Form

Selecting an incorrect ITR form is one of the most common income tax filing mistakes.

The correct form depends on factors such as:

• Type of income
• Salary or pension income
• Business or professional income
• Capital gains
• Number of house properties
• Foreign assets or foreign income
• Residential status
• Eligibility for presumptive taxation

For example, an eligible salaried taxpayer with simple income may be able to use ITR-1, while a person with capital gains or certain additional disclosures may need a different form. Taxpayers with business or professional income may need ITR-3 or ITR-4, depending on their circumstances and eligibility.

Before filing, read our detailed guide:

Choosing the Right ITR Form for AY 2026–27: ITR-1, ITR-2, ITR-3 & ITR-4 Explained

Do not select an ITR form only because you used it in the previous year. Review your current financial information and the applicable eligibility conditions.

2. Not Checking AIS Before Filing ITR

The Annual Information Statement (AIS) provides a comprehensive view of information available to the Income Tax Department. It may include details relating to salary, interest income, securities transactions, mutual fund transactions, tax deductions, and other reported financial information.

Ignoring AIS may result in:

• Missing income in the ITR
• Differences between reported information and return details
• Incorrect reporting of interest or investment income
• Possible follow-up or clarification requirements

Before filing your return:

✓ Download and review AIS
✓ Check whether the information belongs to you
✓ Compare the information with your own records
✓ Review any differences carefully
✓ Provide feedback where appropriate

AIS should be reviewed carefully, but taxpayers should not automatically copy every entry without checking supporting records and the applicable tax treatment.

3. Not Matching Form 26AS with TDS and Tax Details

Form 26AS contains important tax credit information, including applicable TDS, TCS, advance tax, and self-assessment tax details.

A mismatch may occur when:

• TDS details are entered incorrectly
• The employer or deductor has reported incorrect information
• Tax credits are claimed incorrectly
• Challan details are entered incorrectly
• A tax payment has not been properly reflected

Before submitting the ITR, compare your tax credit details with Form 26AS and verify the relevant information.

This can help reduce the risk of tax credit mismatches and refund delays.

4. Forgetting to Report Interest Income

Many taxpayers report salary income but forget income earned from:

• Savings bank accounts
• Fixed deposits
• Recurring deposits
• Post office deposits
• Other interest-bearing investments

Interest income may be taxable according to the applicable provisions. Do not assume that income is not required to be reported simply because the amount is small or because TDS was not deducted.

Check your bank statements, interest certificates, AIS, and other financial records before filing.

5. Not Reporting Income from All Sources

One of the major ITR filing errors is reporting only salary income while missing other sources of income.

Depending on the taxpayer’s situation, income may arise from:

• Salary or pension
• House property
• Bank interest
• Fixed deposits
• Freelancing or consulting
• Business activities
• Capital gains
• Dividends
• Family pension
• Other taxable sources

Make a complete income checklist before filing your Income Tax Return.

6. Reporting Incorrect Capital Gains

Taxpayers who sell shares, mutual funds, property, or other capital assets should carefully calculate and report capital gains.

Common capital gain mistakes include:

• Using incorrect purchase cost
• Using incorrect sale value
• Missing eligible expenses
• Applying the wrong holding period
• Reporting gains in the wrong category
• Ignoring capital gains reported in statements or AIS

Capital gains taxation can be complex. Review transaction statements and applicable tax rules before filing.

7. Claiming Incorrect Deductions

Tax deductions can reduce taxable income when claimed correctly. However, claiming deductions without checking eligibility can create problems.

Common errors include:

• Claiming deductions without supporting documents
• Claiming more than the eligible amount
• Claiming the same benefit twice
• Claiming deductions not available under the selected tax regime
• Entering incorrect policy or investment information

Common deductions may include eligible benefits under:

• Section 80C
• Section 80D
• Section 80G
• Other applicable provisions

Always verify eligibility, limits, payment conditions, and the tax regime before claiming a deduction.

8. Choosing a Tax Regime Without Comparing Tax Liability

Many taxpayers select the old or new tax regime without calculating tax under both options.

The better regime depends on factors such as:

• Total income
• Salary structure
• Eligible deductions
• HRA benefits
• Home loan-related benefits
• Tax-saving investments
• Other exemptions and deductions

The Old Tax Regime may be beneficial for some taxpayers with significant eligible deductions and exemptions. The New Tax Regime may be beneficial for taxpayers with fewer deductions or a different income profile.

Read our detailed comparison:

Old Tax Regime vs New Tax Regime for AY 2026–27: Which Tax Regime Should You Choose?

Do not choose a regime based only on general advice. Compare your own estimated tax liability.

9. Entering Incorrect Bank Account Details

Incorrect bank details may affect income tax refund processing.

Before filing, verify:

✓ Account number
✓ IFSC code
✓ Bank account status
✓ Correct account selection for refund
✓ Whether the bank account is properly validated on the portal

Use an active bank account and review the information carefully.

10. Forgetting to Verify the ITR

Submitting the ITR is not always the final step. The return generally needs to be verified through an available verification method.

Common e-verification methods may include:

• Aadhaar OTP
• Net banking
• Bank account-based verification
• Other available electronic methods

If the return remains unverified, it may not be processed as expected.

After filing:

1. Check the return status
2. Complete e-verification within the applicable time
3. Save the acknowledgement
4. Confirm that the verification status is updated

11. Filing the ITR at the Last Minute

Waiting until the final day may increase the risk of:

• Missing documents
• Portal traffic or technical issues
• Incorrect data entry
• Rushed tax calculations
• Missing deductions
• Delayed verification

File early whenever possible. Early filing gives you time to review the return and correct any errors before the applicable deadlines.

12. Ignoring the ITR Due Date

Missing the applicable due date may result in consequences such as:

• Late filing fees, where applicable
• Interest, where applicable
• Restrictions on carrying forward certain losses
• Delay in refund processing
• Loss of certain benefits or options, depending on the applicable provisions

The due date may vary according to the taxpayer category and applicable requirements. Always verify the latest due date from official sources before filing.

13. Using Incorrect Personal Information

Incorrect personal details may create processing or verification issues.

Check:

• PAN
• Name
• Date of birth
• Aadhaar information
• Mobile number
• Email address
• Residential address

Make sure the information is accurate and updated.

14. Ignoring Notices or Income Tax Communications

Taxpayers should regularly check:

• Registered email address
• Mobile notifications
• Income Tax e-Filing portal
• Pending actions or communications

Do not ignore a notice or communication. Review the issue carefully and respond within the applicable time limit.

15. Not Keeping Supporting Documents

Supporting documents may be required for verification, clarification, or future reference.

Keep records such as:

• Form 16
• Form 16A
• AIS and TIS
• Form 26AS
• Bank statements
• Interest certificates
• Investment proofs
• Insurance premium receipts
• Home loan certificates
• Capital gain statements
• Tax payment challans
• ITR acknowledgement

Maintain records in an organized digital folder.

16. Assuming Pre-Filled Information Is Always Correct

The e-Filing portal may provide pre-filled information, but taxpayers should review it carefully.

Pre-filled data may require verification because:

• Information may be incomplete
• A transaction may belong to another period
• Supporting records may show a different amount
• The tax treatment may require additional review

Never submit the return without checking the information.

17. Not Reviewing the Final Tax Calculation

Before submitting the ITR, review:

• Gross total income
• Taxable income
• Deductions
• Tax liability
• TDS and tax credits
• Refund or tax payable
• Interest and applicable fees

If tax is payable, complete the required payment and enter the correct challan details.

18. Not Filing a Revised Return After Discovering an Error

If you discover an error after filing, check whether a revised return can be filed within the applicable timeline.

Examples include:

• Missed income
• Incorrect deduction
• Wrong bank information
• Incorrect capital gain details
• Incorrect tax information

Do not ignore a genuine error. Review the available correction options and applicable deadlines.

19. Not Taking Professional Help for Complex Income

Self-filing may be suitable for straightforward cases. However, professional assistance may be useful when you have:

• Business income
• Professional income
• Multiple properties
• Capital gains
• Foreign income or foreign assets
• Complex deductions
• Tax notices
• Large or unusual transactions

A qualified tax professional can help review the applicable rules and reduce avoidable errors.

ITR Filing Checklist for AY 2026–27

Before submitting your return, check the following:

✓ Correct ITR form selected
✓ Personal details verified
✓ Salary and pension income checked
✓ Interest income included
✓ Other income reported
✓ AIS reviewed
✓ Form 26AS checked
✓ TDS details matched
✓ Capital gains reviewed
✓ Eligible deductions verified
✓ Correct tax regime selected
✓ Bank details checked
✓ Tax calculation reviewed
✓ Tax payment details entered correctly
✓ ITR submitted
✓ ITR e-verified
✓ ITR acknowledgement downloaded

Frequently Asked Questions

1. What are the most common ITR filing mistakes?

Common mistakes include selecting the wrong ITR form, missing income, ignoring AIS, failing to match Form 26AS, claiming incorrect deductions, entering wrong bank details, and forgetting to e-verify the return.

2. What happens if I select the wrong ITR form?

Using an incorrect form may result in a defective return issue, processing delays, or the need to correct or revise the return, depending on the circumstances.

3. Should I check AIS before filing ITR?

Yes. AIS should be reviewed before filing because it provides information reported to the Income Tax Department. Compare it with your own records and verify the applicable tax treatment.

4. Is Form 26AS important for ITR filing?

Yes. Form 26AS helps taxpayers review tax credits such as TDS, TCS, advance tax, and self-assessment tax information.

5. Can I revise my ITR after filing?

If an error is discovered, a revised return may be available subject to applicable rules and timelines. Check the current provisions before taking action.

6. What happens if I forget to e-verify my ITR?

An unverified return may not be processed. Complete verification through an available method within the applicable timeline.

7. Can I change my tax regime while filing ITR?

The availability and method of choosing or changing a tax regime depend on taxpayer category, income type, and applicable rules. Review the current requirements before filing.

8. Why is my income tax refund delayed?

Possible reasons include pending verification, incorrect bank details, tax credit mismatches, incomplete information, or processing delays.

9. Do I need to report bank interest in ITR?

Interest income may need to be reported according to the applicable tax provisions. Review bank records, AIS, and other relevant documents.

10. Should I file ITR myself or take CA assistance?

Simple cases may be suitable for self-filing. Professional assistance can be useful for business income, capital gains, foreign assets, multiple income sources, or complex tax situations.

Conclusion

Avoiding common ITR filing mistakes is essential for accurate income tax compliance. Before filing your return for AY 2026–27, select the correct ITR form, review AIS and Form 26AS, report all applicable income, verify deductions, compare tax regimes, check bank details, and complete e-verification.

A careful review before submission can help reduce errors, avoid unnecessary follow-up, and support smoother ITR processing.

For a complete step-by-step overview, read our Complete Guide to ITR Filing for AY 2026–27: Everything You Need to Know.

You may also find these related guides helpful:

Choosing the Right ITR Form for AY 2026–27: ITR-1, ITR-2, ITR-3 & ITR-4 Explained

ITR Filing FAQs 2026: Common Income Tax Return Questions Answered

Old Tax Regime vs New Tax Regime for AY 2026–27: Which Tax Regime Should You Choose?