If you have received any portion of your salary in arrears or in advance, or you have received the family pension in arrears, you are allowed some tax relief under section 89(1) read along with Rule 21A.
Here’s how you can calculate the tax relief yourself –
Step 1: Calculate tax payable on the total income, including additional salary – in the year it is received.
Arrears provided for will reflect in Part B of Form 16.

Step 2: Calculate tax payable on the total income, excluding additional salary in the year it is received. You can get the amount of the additional salary (Arrears) from the arrear document given by your employer.
Now you have to subtract the arrear from the total salary received (including the arrears), which can be taken from your Form 16.
After knowing the amount after arrear, you need to calculate the tax over the same.
Step 3: Calculate the difference between Step 1 and Step 2.
Step 4: Calculate tax payable on the total income of the year to which the arrears relate, excluding arrears.
Step 5: Calculate tax payable on the total income of the year to which the arrears relate, including arrears
Step 6: Calculate the difference between Step 4 and Step 5.
Step 7: Excess of amount at Step 3 over Step 6 is the tax relief that shall be allowed.
If the amount in Step 6 is more than the amount in Step 3 no relief shall be allowed.
Alternatively, you may follow the steps on the income tax website to calculate the tax the arrears.
Once you have calculated this amount you can enter the values on ClearTax and proceed to file your return.