Why does the amount in my CPF Medisave Account (MA) increases over time? Isn't there a cap to the maximum amount?

You can save up to the prevailing Basic Healthcare Sum (BHS) in your MediSave Account if you have not turned age 65. The BHS from 1 January 2021 is $63,000 for all CPF members aged 65 years old and below in 2021. The BHS applicable to you will be adjusted yearly to account for increasing life expectancy and healthcare costs until the year you turn age 65. What this mean is that while there is a cap, this cap increases each year which the system accounts for automatically.

Source: CPF Website, FAQ

If you have not reached the maximum amount when you reach 65, if you are still contributing to your CPF, part of it will continue to be distributed to your CPF-MA until it reaches the maximum amount as of when you are 65. Your CPF-MA will also continue to enjoy its own capital growth until it reaches the maximum amount before the excess of it will be spilled over to your other CPF accounts.