Interest charges in MTF varies for all users based on the plan mapped to their account. These charges are levied on the debit balance in your trading account.
You can check your statements by following the path on NEO
How can I view the margin required for NRML and Pay Later (MTF)?
Can I use the profit I made by trading in F&O to trade further on the same day?
Why have I been charged a margin penalty?
What happens if I do not pay the balance margin before settlement?