Possible Bug: 2025 TurboTax Online - HSA Last Month Rule calculation incorrect

[TeaTax23]

Found what appears to be a bug using 2025 TurboTax Online.  Any avenue I try to take to talk to someone at TurboTax involves pulling out a credit card so turning here for support / confirmation.

Contributed the max ($4,150) to my HSA in 2024 using the Last Month Rule, but failed the Testing Period for 2025.

After filling out the HSA section, the amount of Additional Income it says I have to report is less then what I calculated by hand, by exactly one month ($346).

After going back and forth testing, the problem seems to be that the January drop down in the "2024 Coverage by Month" section is the source of the issue.  If you put None, it acts like Self plan, and if you put Self plan, it acts like None.  In other words, if you put Self plan for ALL months, it reports Additional Income due of one month ($346), but if you change January to None, it reports $0 Additional Income.  I did not test with Family plan.

It does allows you to directly edit the Additional Income number so it's easy to work around the problem, but I wanted to confirm this is incorrect behavior and not a misunderstanding on my part.  Anyone else seen this?

[BillM223]

This issue appears to have been rectified. Please let us know if you see it again.

[402donnelly]

Unfortunately, the HSA last-month rule calculation issue has not yet been resolved. As of February 18, 2026, I am experiencing the same errors reported by the original poster while using TurboTax Premier Desktop. I would greatly appreciate any guidance or assistance. Thank you.

[BillM223]

Does the workaround of setting the month of January 2024 to None (obtusely causing this month to be set to Self) work for you?

@402donnelly 

[402donnelly]

Thank you @BillM223

Yes, the workaround of setting January 2024 to none works for me.

With this adjustment, TurboTax’s statement now reflects a zero value: “We calculated [zero] of income must be included in your return this year because of the last-month rule. In rare circumstances, you may need to change this number if your marital status changed in 2024 or 2025.”

[TeaTax23]

@BillM223 

First time revisiting this since your reply.  As of this post, I am still seeing the same issue as originally described. (TT Deluxe Online)

[big red]

Bug is still there and workaround works as of 2/19/26. Thanks for the help, unlike TurboTax.

[Wildcard]

This is a bug and is still not fixed as of Feb. 23.

The bug is that 2025 Do It Yourself Premium Online TurboTax is trying to use the "Last-Month Rule" because it incorrectly thinks I did not have a HDHP in January 2024.

100% confirmed that if you switch HSA in January from "self" to "none" that the extra income is not applied.

If I switch my January 2024 HDHP coverage from "none" to "self", it applies extra income plus 10% penalty thinking that I broke the "last-month rule"

My Setup:  I had a HDHP every month of 2024 and contributed the max amount of $4,150 to my HSA in 2024.  In 2025 I had a HDHP for 10 of the 12 months.  During the 2 months of not having a HDHP I did not contribute to my HSA.  

Some people have been saying just to leave January 2024 as "none" to trick the software, but I will not be making false statements.  I should not have to lie to the tax software that I am paying $99 for to get it to work.

Since TurboTax has known about this bug and have not fixed it in over 3 weeks, I will be switching to another tax software that has earned the $99 fee.

I have been using TurboTax for over 8 years and I am very disappointed that they are de facto forcing me to switch to another company.

[BillM223]

There is a process on investigating and correcting software issues. This issue has entered the Investigation stage in which the issue is confirmed and test case set up. The next step is to pass that to the development team for correction. There is no ETA yet on the rollout of a fix.