Every person who has been allotted a Permanent Account Number (PAN) and is eligible to obtain Aadhaar number, must link their PAN with Aadhaar as per provisions of Section 139 AA of the Income Tax Act 1961. Further non linking of PAN with Aadhaar shall make PAN “inoperative" and
1. TDS / TCS would be deducted /collected at Non PAN rate (including cash withdrawal) ,
2. Form 15G/H with inoperative PAN will not acceptable
3. Existing Form 15 G / H becomes ineffective till PAN remains inoperative.
4. As per NSDL / CDSL guidelines, Demat account opening & transactions processing will be restricted for inoperative PAN.
5. As per extant RBI guidelines investment in RBI Bonds is not allowed for inoperative PAN.
6. As per extant RBI guidelines investment in Sovereign Gold Bonds is not allowed for inoperative PAN.
7. As per SEBI guidelines, ISA account opening and transactions processing will be restricted for inoperative PAN.

Here are two useful links for you:
Click here to check the status of your PAN – Aadhaar linkage
Click here to link your Aadhaar with PAN