From FY 2023-24 on words those who opted Old Regime after due date [ 31st July ] automatically converted into New Regime.
Those who opted New Regime after due date late fee of Rs.5,000, which shall be reduced to Rs.1,000 if your total income is below Rs.5 lakh.

Section 80CCD(1B) of Income Tax Act

In this Section an additional deduction up to Rs. 50,000 for contributions made by individual taxpayers towards the NPS (Tier-I account).

It is applicable only an Old Regime.

National Pension System(NPS) contains two types of accounts.They are Tier-I and Tier-II.

Tier-I accounts are fixed lock-in period until the subscriber reaches the age of 60 years. Only partial withdrawal is allowed, with certain conditions.It is eligible to claim the deduction under Section 80CCD(1B).

Tier-II accounts are not eligible to claim the deduction under Section 80CCD(1B)

80C + 80CCC + 80CCD(1) + 80CCD(1B) = 2,00,000.