If you are enrolled in Medicare in 2018, you cannot contribute to a HSA even if you had a HDHP and "Medicare is an unused backup".
Please read this document:
https://www.benstrat.com/downloads/HSA-GPS_HSAs-and-Medicare.pdf
**Say "Thanks" by clicking the thumb icon in a post
**Mark the post that answers your question by clicking on "Mark as Best Answer"
