I thought HSA was taxable in NJ, AL and CA only. someone just told me it's also taxable in MI and IN, is that true? i can't find backup to support that

[BMcCalpin]

It is difficult to prove a negative. The states that allow HSA contributions to be tax free simply don't mention the HSA contributions as an adjustment to federal income. Their codes are not going to state that "HSA contributions are tax-free", because they don't need to - they're tax-free on the federal return.

However, if you go to websites like the Optum Bank website (a large provide of HSA accounts), they would certainly keep up with state laws. Optum Bank reports that only three states do not allow HSA contributions to be deducted  - See https://www.optumhealthfinancial.com/individualsfamilies/hsataxresourcecenter/statetaxinformation.ht...

There are a lot of old pages on the Internet that date from the 2004 timeframe (when HSAs began) that state that all sorts of states do not allow for HSA contributions - but that was 14 years ago.