If they no longer have an HSA-qualified health insurance plan, they can't contribute to their HSA. However, HSA usage is not defined by eligibility. While they can no longer contribute to their HSA, they can still pay for qualified out-of-pocket medical expenses with their HSA, allow the account to accrue interest, invest the funds, or use them for qualified medical expenses.
Read more about the ways to use HSA funds once HSA-eligibility is lost.
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