In May, the central government had extended the deadline to link Aadhaar with ration card to 30 September 2020. These two key official identity proofs in India are required to obtain food grains at subsidised rates.
Linking the two has been mandatory to avail the maximum benefits of the government's social welfare schemes. Note that the government had assured that those who had failed to link Aadhaar with ration card will not be deprived of food grains.
The two documents can be linked online as well as offline. You will need photocopies of ration card, copies of Aadhaar card of all members of the family and a passport size photo of the head of the family. One will also need a copy of bank passbook in case the bank account has not been linked with Aadhaar.
The UIDAI (official authority that issues Aadhaar) in its website says, "We recommend that you submit a photocopy of your Aadhaar with a copy of ration card to your PDS shop. They may ask you to place a finger on a sensor to authenticate to check that you and your Aadhaar number are matched."