The IRS has updated its website FAQ this month about deadlines, including those related to Health Savings Accounts and Archer Medical Savings Accounts.

Q. Does this relief provide me more time to contribute money to my HSA or Archer MSA for 2019?

A.  Yes. Contributions may be made to your HSA or Archer MSA, for a particular year, at any time during the year or by the due date for filing your return for that year. Because the due date for filing Federal income tax returns is now July 15, 2020, under this relief, you may make contributions to your HSA or Archer MSA for 2019 at any time up to July 15, 2020.  For more details on HSA or Archer MSA contributions, see Publication 969, Health Savings Accounts and other Tax-Favored Health Plans.

Read more under this an other topics included in the IRS Q&A at irs.gov/newsroom/filing-and-payment-deadlines-questions-and-answers