Effective 2020 the allowable contribution for an individual HSA is $3,550 and for a family it is $7,100.

You can use them until you can’t – and then you must let them go – Commuter Benefits 

In Information Letter 2019-02, the IRS has confirmed that unused transportation benefits will be forfeited when an employee terminates employment.  It does not matter how much or why – when the employee is no longer actively employed, the remaining balance in the account is forfeited.