You think you will get your investment in PPF after 15 years . However perhaps it might get a compulsory 16 years lock-in period.
Because the year in which you open your PPF account then the current financial year is considered as zeroth year. from the next year it is considered as first year. It means if you have opened your PPF account on 01st June 2021 then from 2021-2022 will not be counted. From April 2022 onwards it will be counted as first year and after 15 years from this day you will get your investment amount.
It means after completing 15 years and 10 months you will get the maturity amount.
Of course you will get interest on these extra 11 months. But the date of maturity date will extend further. So do make your plans accordingly.
Tip about investing in PPF
When you invest in PPF do the investment before 05th of each month because o5th is considered as the cutoff date for PPF investment. You will not interest on the amount invested for the same month if you will pay after 05th day of this month.