Little known fact for those over age 55: In the year you turn 55, you can start contributing an extra $1,000 to your HSA, and so can your spouse! The trick is that your spouse must open and contribute to their own account.
The normal IRS limits for a family plan HSA (or a couple plan) is $7,000 per year (2019 limits). Your employer plus employee contributions cannot exceed this limit. However, in the year you turn age 55 until you sign up for Medicare, your limit increases to $8,000. The year your spouse turns 55, they can also add $1,000 (albeit to their own account, not your account), for a total of $9,000 per year in contributions! Even some professional tax software does not account for this correctly, so make sure you are getting the full tax benefit of your contributions.
Note that if you are not married, the extra over 55 limit is still $1,000. You just add the total $4,500 to your own HSA.