Coverage End date for current plan

Summary: Need to have Coverage End date for current plan along with coverage start date when election made.

Content (required):

Hi All,

We have a Commuter plan where employer gives a subsidised amount and it is entered during enrollment (say 1000). This amount should be deducted on every payroll for a year. This is working fine. We need to end date this enrollment automatically when 1000 amount got deducted completely.

Say employed enrolled into this plan 08/01/2021 and deducted money for one year, should end date on 07/31/2022. How can we acheive this functionality? I tried for temporal event but derived factors not there for such criteria. Please suggest an amicable solution