Does California Tax Your HSA? What It Changes at Open Enrollment

California never adopted IRC Section 223, so an HSA contribution gets no California deduction. The full 2026 federal limit, $4,400 self-only or $8,750 family, is added back to your California income, and the interest and gains inside the account are taxed by California every year they accrue.

Two things are tangled in this election

Two things, and they move independently.

First, the health plan itself. Deductible, network, premium, what your household actually spent on care last year. That is a coverage question and it has nothing to do with tax.

Second, the HSA that rides along with the high deductible plan. That one is a tax question, and in California it is a different tax question than the one the national articles answer.

For now, let’s forget about the coverage side. It matters, but it is yours to work out with the plan documents in front of you. This walks through the second one, which is the piece that gets left out.

What the federal rules give you for 2026

Per IRS Revenue Procedure 2025-19, effective for calendar year 2026, the annual HSA contribution limit is $4,400 for self-only coverage and $8,750 for family coverage. The same revenue procedure defines a 2026 high deductible health plan as one with an annual deductible of at least $1,700 self-only or $3,400 family, with out-of-pocket expenses capped at $8,500 self-only and $17,000 family.

The age 55 catch-up adds $1,000 on top. Keep in mind that one is written into IRC Section 223(b)(3)(B) as a flat number and is not indexed, so it does not move each year the way the other figures do.

Nothing above is in dispute. It is also not the whole return if you file in California.

What California does with the same dollars

California has no provision comparable to IRC Section 223. Not a gap that got quietly patched, and not a filing quirk. It is the current law, and it shows up in three separate places on your state return.

Your own contribution comes back. The 2025 Instructions for Schedule CA (540), California Adjustments put it on line 13: federal law allows the deduction, California law does not conform, and the federal amount is entered in column B as an addition.

Your employer’s contribution comes back too. Whatever appears in box 12, code W on your W-2 goes to line 1h, column C, and lands in your California wages. That one surprises people, because it never touched their paycheck.

And the account does not compound untaxed for California. From the same instructions:

"Interest or earnings in an HSA are taxable in the year earned."

2025 Instructions for Schedule CA (540), California Adjustments, Franchise Tax Board

That third one is the one that gets missed, because it is not a single event. It is an annual reporting item for as long as you hold the account, and the same instructions treat gain or loss from selling investments inside the HSA as reportable for California as well. A federally invisible account is a California reporting account.

The same 2026 dollars, side by side

Sources: IRS Revenue Procedure 2025-19, effective calendar year 2026 (limits and plan thresholds). 2025 Instructions for Schedule CA (540), California Adjustments, Franchise Tax Board (California line references and treatment). Line references are to the 2025 form and may renumber on the 2026 revision.

Where California is actually better, which is worth saying first

The last two rows run the other direction, and anyone arguing the other side of this would raise them, so here they are.

A distribution you took for something other than a qualified medical expense gets picked up in federal income. California subtracts it back out, because those were already California-taxed dollars going in. And expenses you paid with a tax-free HSA distribution can still count toward the California itemized medical deduction above 7.5% of federal adjusted gross income, which the federal return does not allow.

Neither of those offsets the annual earnings pickup on a large invested balance. But they are real, and a post that only listed the costs would be selling you something.

Running the arithmetic once

A hypothetical. Not a client, not a projection, and the inputs are chosen to make the math visible.

Family high deductible plan, contributes the full $8,750 for 2026, employer adds nothing, account invested rather than sitting in cash. Pick a round 9 percent for California. That is a placeholder, not a bracket lookup and not your rate. On $8,750 the lost state deduction runs about $787 for the year. If the account throws off $400 of interest and dividends, add roughly another $36. Call it a little over $800 in year one, and the earnings piece repeats every year and grows as the balance grows.

Keep in mind the federal deduction on that same $8,750 does not disappear, and at a high federal marginal rate it is worth more than the California add-back costs. That is arithmetic to run on your own return rather than a rule, but the direction is not close. The point is not that the HSA stops working in California. The point is that the number in the national article is not the number on your return, and it is smaller every year the balance gets bigger.

The HSA is also one of the few accounts built for a cost that arrives later. Where it sits in the withdrawal order once you get there is its own separate question.

Name what is not going to change

AB 781 would have allowed a California HSA deduction in modified conformity with federal law for tax years 2026 through 2030. It did not pass. The bill was filed with the Chief Clerk under Joint Rule 56 on February 2, 2026, which is how a California bill ends without a floor vote. AB 727 in 2021, and AB 1140 and AB 989 in 2017, ended the same way.

The Franchise Tax Board’s own analysis of AB 781, amended March 28, 2025, estimated that roughly $920 million of HSA contributions and employer contributions would have been deducted or excluded by Californians in taxable year 2026, and put the state’s revenue loss from conforming at about $70 million using an average 7.5 percent rate. That $70 million is the aggregate version of what shows up on your return as one add-back line.

So the baseline for the window in front of you is non-conformity. Nothing pending changes it before your election is due.

What to confirm before the window closes

Four things, in order, and the last one is the irreversible one.

First, pull last year’s W-2 and look at box 12 for a code W. If there is a number there, confirm with your CPA whether it was added to your California wages.

Second, ask your HSA custodian what California reporting it provides. Some send a year-end summary of interest and dividends and some do not, and the reporting obligation sits with you either way.

Third, if the account is invested rather than in cash, confirm with your CPA or tax advisor how gains inside it are reported for California in a year you rebalance.

Fourth, before you submit the election, evaluate the high deductible plan and the PPO on premium and expected out-of-pocket spend first, then look at the California HSA treatment as an adjustment to the HSA side rather than as the variable that decides it.

None of that tells you which plan to elect, and it is not meant to. Two people at the same employer on the same salary land in different places on this, and the input that usually decides it is expected medical spend, which is not a tax question at all. Your CPA or tax advisor is the one who can price the California side against your actual return. This is education, not tax advice.

The state add-back is small on its own. It stops being small once it is stacked against the deferral election, the vest schedule and the withholding decision that all land in the same quarter, which is the coordination the San Diego H.E.N.R.Y. Strategy page is built around.

Questions that come up

Does California tax HSA contributions?

California does not allow a deduction for HSA contributions. The federal deduction is added back on Schedule CA (540), line 13, column B, so the full amount stays in California taxable income for the year it was contributed.

Does my employer's HSA contribution get taxed in California?

Yes. The amount reported on federal Form W-2, box 12, code W is entered on Schedule CA (540), line 1h, column C, which adds it to California wages even though it was excluded federally.

Are HSA earnings taxable in California every year?

Yes. The 2025 Instructions for Schedule CA (540) state that interest or earnings in an HSA are taxable in the year earned, and that gain or loss from selling investments inside the HSA is reportable for California as well.

Does California non-conformity mean a high deductible plan is the wrong choice?

No. It is one input, not the answer. The premium difference, expected out-of-pocket spend, and the federal deduction all still count. Confirm how the California side lands on your own return with your CPA or tax advisor.

Has California ever tried to conform to the federal HSA rules?

Several times. The most recent attempt, AB 781, would have allowed a California HSA deduction for tax years 2026 through 2030. It was filed with the Chief Clerk under Joint Rule 56 on February 2, 2026 without passing.

If it would help to run your own numbers

BAS Financial works with San Diego high earners on this kind of fork, where the federal answer and the California answer point in different directions and the deadline is set by someone else’s enrollment calendar. The San Diego H.E.N.R.Y. Strategy page covers how these pieces get sequenced. A complimentary review can be scheduled here, and what an engagement costs is discussed during that review.

Which plan does your employer put you in if you do nothing?