When must HSA contributions stop?
Once an individual enrolls in Medicare, contributions, including catch-up contributions, cannot be made beginning with the month the individual enrolls.
EXAMPLE: Pearl, who is covered under an HDHP with self-only coverage, attains age 65 and enrolls for Medicare benefits on March 1, 2018. Her 2018 contribution limit is 2/12 of the statutory contribution limit. She may make contributions for January and February, but may not make any contributions for March through December 2018 or thereafter.