Click the below link and the income tax India filling website will open. Then click log in if you have already an account. otherwise, if you don't have an account click register and enter your pan number and password all details. after that login your account with your login id and password the date of birth. after login go to profile setting in that Link Aadhar tap available. Click the Link aadhar tap the enter your aadhar number and your date of birth. if it matches with your pan database it will accept otherwise it will show an error. once register aadhar number then you click profile setting and check the aadhar status in link aadhar Tab.