If you want to link your Aadhaar with PAN card, head over to the Income Tax e-filing portal and follow the steps below:
On the website, click on the link on the left saying Link Aadhaar.
Now, enter your PAN number, Aadhaar number, name as per Aadhaar, and the Captcha, and then click on Link Aadhaar.
This should link the PAN and Aadhaar, but if there is any discrepancy n your details, you'll receive an Aadhaar OTP to confirm the linkage. Enter the OTP and click on Save to continue.
You can also link the details after logging in to the income tax website. Log in as you normally would and then click on Profile Settings in the top menu.
Next, find Link Aadhaar.
Enter your Aadhaar number and click on Save to continue.
This will only work if the details on the PAN and the Aadhaar card match. In case of any discrepancies, you can upload a scan of your PAN card, or register via OTP on your linked mobile number as mentioned above.