1. PAN is required to pay income tax.
2. Service tax and excise registration can be obtained only if one has PAN.
3. All documents related to financial transactions.
4. Sale and purchase of immovable property.
5. Purchase of any motor vehicle.
6. For depositing cash more than INR 50,000 in bank account or post office.
7. For term deposit (FD) of more than INR 50,000 in bank or post office.
8. PAN card works as an ID proof at many Govt. places.
9. TDS is applicable on interest amount earned by you, you need to provide PAN to your Bank.

There are many other places where PAN is required, specially when it works as an ID proof.

Must Read: What is PAN?