As per section 206AA, if you do not furnish your Permanent Account Number to the payer (i.e., deductor), then the deductor shall deduct tax at the higher of the following rates:
- At the rate specified in the relevant provision of the Act.
- At the rate or rates in force, i.e., the rate prescribed in the Finance Act.
- At the rate of 20%.
Source: Income Tax India’s Official Website