Visit the official website of Income Tax Department - incometax.gov.in/iec/foportal/
Open Quick Links section and select Link Aadhaar Status
Enter your PAN and Aadhar card number
Click on 'View Link Aadhaar Status' option
The screen will show you the PAN-Aadhaar link status
If your PAN card is linked to Aadhaar, the screen will show Linked otherwise, it will show the link to link both the cards.