HSA Through Your Employer

No. Your employer only needs to offer an HDHP - if they do, you can open an HSA at any IRS-approved trustee (Fidelity, Lively, HSA Bank) on your own. But the FICA savings only work via employer payroll deduction under Section 125. If you contribute to a personal HSA outside payroll, you still get the federal income tax deduction on Form 8889, but you miss the 7.65% FICA savings that the W-2 payroll route gives you.

YES - this is the most common employee mistake. The 2026 combined cap is $4,400 self-only or $8,750 family, and BOTH your payroll contribution and any employer contribution count against the same bucket. If your employer puts in $1,000 and you put in $4,000 self-only, you have over-contributed by $600 and owe a 6% excise tax on the excess until corrected. Always subtract the employer contribution from the cap before setting your payroll election.

Employer-specific, but most US employers run open enrollment somewhere between mid-October and early December for a January 1 effective date. The HSA election lives inside the same benefits enrollment as the HDHP election - you cannot choose the HSA without first choosing the HDHP. Mid-year enrollment is only available with a qualifying life event (marriage, divorce, birth or adoption, loss of dependent coverage, employment status change, or residence change). QLE deadlines are usually 30 days from the event.

For most employer plans, yes. The IRS allows participants to change HSA contribution amounts at any time under Section 125 - the limit is that the underlying election to participate in the HSA is annual unless a qualifying life event occurs. Check your benefits portal: many large employers let you adjust the per-paycheck dollar amount monthly or even per-paycheck. Small employers sometimes lock the dollar amount until next open enrollment.

It stays with you. The HSA belongs to you, not the employer - that is true whether you quit, get laid off, retire, or move. After you leave, you can keep the account at the employer-selected provider, or do a trustee-to-trustee transfer to a different provider (Fidelity and Lively are the two most common destinations for people escaping high-fee employer HSAs). Trustee-to-trustee transfers are unlimited per year, tax-free, and reportable but not taxable.

No. Employer HSA contributions are tax-free to you - they do not appear in Form W-2 Box 1 wages, and you do not pay income tax or FICA on them. They DO show up in W-2 Box 12 code W alongside your own payroll contributions, which is how the IRS tracks the total against the annual cap. The only way an employer contribution becomes taxable is if it pushes you over the IRS cap and you fail to correct the excess by your tax-filing deadline.

Yes, if you maintain HDHP coverage. Three common paths after a mid-year job exit: (1) elect COBRA HDHP continuation - you keep contributing to the HSA, just losing the payroll tax-advantaged route; (2) start a new job with a new HDHP - HSA contributions resume via the new employer's payroll; (3) buy a marketplace HDHP - you contribute on your own and claim the deduction on Form 8889. If you switch to non-HDHP coverage (a PPO at a new employer, Medicare, etc.), contributions stop and your annual limit prorates by the months you were HSA-eligible.

Section 125 of the Internal Revenue Code lets employers run a cafeteria plan that makes specific employee elections pre-tax for federal income tax AND for FICA (the 7.65% Social Security + Medicare payroll tax). HSA contributions are one of the eligible elections. When you choose payroll HSA contributions, your taxable wages drop by the contribution amount before FICA is calculated - you save 7.65% on top of your income tax savings. Your employer ALSO saves their 7.65% FICA match on the same dollars. Self-employed people get the income tax savings on Form 8889 but cannot reach the FICA layer because they pay both halves of SE tax on net business income before any HSA adjustment. This is the unique advantage of the employer-payroll path.