There are two ways to link your PAN Card to your Aadhaar card.

Linking online

All you need to do is log into the Income Tax India’s e-filing portal. Once you log into your account, you will find the option 'Link Aadhaar'. Click on ‘Link Aadhaar’ and you will be greeted with a window that asks you to key in your PAN and Aadhaar numbers.

It will ask other details like your name and gender and asks you to enter a capcha. Once you key in all details, click on the option to link your PAN card to Aadhaar.  In case of a small mismatch in the names on both cards, it will ask you for an OTP that will be sent to your mobile number.

Linking using SMS

You can link your PAN card to Aadhaar card by sending an SMS on 567678 or 56161. The SMS format should be – UIDPAN <SPACE> <12 digit Aadhaar> <Space> <10 digit PAN>.

Linking your pan card to Aadhaar card doesn't require you to share any documents, but in case details on both documents don't match, then you may be required to share more proof. However, the SMS facility is only for users whose names are identical on Aadhaar and PAN cards.