Failing to do so can result in freezing of your mutual funds accounts. Here's how you can link your Aadhaar to your mutual fund account:
Online Method
CAMS or Computer Age Management Systems is a Registrar and Transfer agent that covers major mutual fund houses in the country. CAMS provides an online form which allows you to register your Aadhaar number to your mutual fund account. You can visit the CAMS website by clicking here. Alternatively if your mutual fund products are servicesd by Karvy Computershare, you can visit this website to link you Aadhaar.
Sundaram BNP Paribas Fund Services (for BNP Paribas Mutual Fund and Sundaram Mutual Fund) also has an online tool for Aadhaar-mutual funds linkage.
Registering with the fund house
If you are dealing with a single fund house or have freshly zeroed in on an investment service, you can connect your aadhaar to your account after you start investing. For example if you use SBI's mutual funds services, you can visit its website and start your Aadhaar-based eKYC. Enter your PAN and choose the option that says you are not KYC-compliant. You will then be asked details like your mobile number (make sure you key in the same number that is registered with Aadhaar) and other details.
Physical KYC
Alternatively you can download the KYC form, which is available on websites of all the fund houses, registrar and transfer agents and Association of Mutual Funds of India, the trade body for the mutual fund industry. You can also download the form here.
You can submit your completed KYC application form at any of their branches or at any fund house. Don't forget to take along your original supporting documents and their copies as well.