How does turbotax calculate excess contribution to hsa

[MaryK4]

For 2021, the maximum combined total that you, your employer, and/or any other eligible person can contribute to your HSA account is:

• $3,600 if you're under 55 at the end of 2021 and are covered by an individual (self-only) HDHP;
• $7,200 if you're under 55 at the end of 2021 and are covered by a family HDHP;
• $4,600 if you're 55 or older at the end of 2021 and are covered by an individual (self-only) HDHP;
• $8,200 if you're 55 or older at the end of 2021 and are covered by a family HDHP.

See Why am I showing an excess HSA contribution in 2021?

[Mike9241]

the law specifies a pro rata amount for each month covered by a qualified high deductible plan.  example annual $3600 per month $300

but there are quirks.  you can't contribute starting with the month you go on medicare. if you're married and your spouse covers you with your insurance that is not a HDHP - nothing can be contributed.  if you and your spouse each have HDHP, the lowest deductible of either plan must be the minimum for what's required by a HDHP.   if you have other general health insurance that is not a HDHP - no contribution.  if you have no HDHP coverage for 11 months but starting  12/1/2021 you are covered by a HDHP and have no disqualifying coverage you can make a full year's contribution.  however, you must remain covered by a HDhP through 12/31 of the following year.

there are other quirks so if you want to know about your specific situation you need to post full details