"Any additional guidance/resources that can help me make sense of the 'personal' vs 'employer' distinction here?"
"Employer" contributions are any contributions made through the employer (i.e.,...
See more...
"Any additional guidance/resources that can help me make sense of the 'personal' vs 'employer' distinction here?"
"Employer" contributions are any contributions made through the employer (i.e., the code W in box 12 on your W-2), no matter what the source of the dollars was. "Personal" contributions are all other contributions, i.e., not made through the employer, not matter what the source was.
This is the IRS' terminology and it causes no end of confusion.
Simply put, the contributions on your W-2 are removed from Wages in boxes 1, 3, and 5 on your W-2, while the other contributions are shown on line 13 on Schedule 1 (1040).
So if your excess contributions are from the "personal" contributions, then there is no adjustment to the "employer" contributions on the HSA Summary, but only to the personal contributions on lin13 on Schedule 1 (1040< which will be reduced by the excess.
When you get the excess message from TurboTax, you will be asked if you want to withdraw all of it, some of it, or none of it. If you don't withdraw all of it, the balance will carry over to next year. You will be dinged a penalty of 6% of either the excess or the value of your HSA on December 31, 2025, which ever is smaller. This is why you are asked about the value of your HSA.
A similar thing is true for your Roth IRA - TurboTax is calculating a penalty, probably for excess contributions to your Roth IRA, but there are many more ways to deal with IRAs so I won't speculate more than that.