Additional Medicare Tax for H-1B Visa Holders (Form 8959)
A 0.9% surtax kicks in when wages exceed $200,000 — but the threshold is different for married couples, and your employer almost certainly under-withheld if you and your spouse both work.
Under-withholding is common for dual-income H-1B couples:
- Each employer withholds the 0.9% surtax only when wages from that employer exceed $200,000. For a married couple each earning $180,000, neither employer withholds a single dollar of Additional Medicare Tax.
- But the MFJ threshold is $250,000 combined. Combined wages of $360,000 means $110,000 is subject to the 0.9% tax — an additional $990 owed at filing that was never withheld.
- If this shortfall pushes your underpayment over safe harbor limits, you may also owe an underpayment penalty on Form 2210.
What Is the Additional Medicare Tax?
The Additional Medicare Tax (AMT) is a 0.9% surtax enacted by the Affordable Care Act and codified at IRC §3101(b)(2). It applies to wages, Railroad Retirement Tax Act compensation, and self-employment income above certain thresholds. It is separate from the standard 1.45% employee Medicare tax and the 0.9% employer Medicare tax. The employer does not pay any portion of this additional 0.9% — it is entirely the employee's obligation.
Form 8959 calculates the Additional Medicare Tax you owe and reconciles it against what was actually withheld from your wages. The net amount flows to Schedule 2, Line 11 of Form 1040.
The Thresholds
| Filing Status | Threshold |
|---|---|
| Single / Head of Household | $200,000 |
| Married Filing Jointly | $250,000 |
| Married Filing Separately | $125,000 |
These thresholds are not indexed for inflation and have not changed since the tax was introduced in 2013.
How Employer Withholding Works — and Why It Falls Short
Your employer is required to withhold the Additional Medicare Tax on wages it pays you that exceed $200,000 in a calendar year, regardless of your filing status or your spouse's income. The employer threshold is always $200,000 per employee, no matter whether you file single or jointly.
This creates a gap for married couples. Consider two scenarios:
Scenario A: One earner over $200k
H-1B earns $250,000. Employer withholds 0.9% on $50,000 = $450. MFJ threshold is $250,000 so actual liability is 0.9% on $0 = $0. You get a $450 credit (over-withheld). No issue.
Scenario B: Both earners under $200k
H-1B earns $160,000, spouse earns $140,000. Combined: $300,000. Neither employer withholds any Additional Medicare Tax. But $50,000 is above the $250,000 MFJ threshold. Liability: $450. Entire $450 is owed at filing.
Scenario B is extremely common in H-1B households where both spouses work at tech companies earning $120,000–$190,000 each. Both employers withhold zero dollars of Additional Medicare Tax, yet the couple owes it at filing.
What Income Is Subject to the Tax
The 0.9% applies to:
- Wages from employment (Box 5 of W-2)
- Railroad Retirement Tax Act compensation
- Net self-employment income (Schedule SE)
It does not apply to investment income such as capital gains, dividends, or interest. Investment income above the same income thresholds may be subject to the separate 3.8% Net Investment Income Tax (Form 8960), but that is calculated on a different form.
Self-Employment Income
If your spouse has H-4 EAD consulting income on Schedule C, the net profit is subject to the 0.9% surtax if combined household income exceeds $250,000 (MFJ). Self-employment income is combined with W-2 wages for the purpose of determining whether you exceed the threshold. Form 8959 has a separate section (Part II) for self-employment income.
There is an important asymmetry: regular Medicare tax on self-employment income at 2.9% is already included in Schedule SE. The 0.9% Additional Medicare Tax is on top of that. For self-employed individuals, none of the Additional Medicare Tax is deductible — only the base 2.9% SE Medicare tax has a 50% deductibility rule.
Common Mistakes
- Assuming employer withholding covers your liability. As shown above, it often does not — especially for dual-income households where neither spouse earns over $200,000 individually.
- Confusing the 0.9% AMT with the 3.8% NIIT. These are two separate taxes. The 0.9% applies to wages and SE income; the 3.8% applies to investment income. Many high-income H-1B filers owe both. See our Form 8960 (NIIT) guide.
- Not adjusting quarterly estimated payments. If you know you will owe Additional Medicare Tax and it is not being withheld, include it in your quarterly estimated payment calculations to avoid underpayment penalties.
- Filing MFS to reduce the threshold. Married Filing Separately lowers the threshold to $125,000 per person, which typically results in more total tax, not less. Avoid MFS unless there is a compelling reason unrelated to this surtax.
How Our Platform Handles This
Our tax engine automatically calculates Additional Medicare Tax on Form 8959 using wages from each W-2, SE income from Schedule SE, and your filing status. It compares the amount withheld (from Box 6 of your W-2) against the actual liability and posts any difference to Schedule 2. If you are a dual-income household under the $200,000 per-employer threshold, the engine flags this gap during data entry so you are not surprised at filing time.
For the full picture of your tax liability see our Form 1040 overview, which shows where Form 8959 fits in the full return.
IRS source: IRS — About Form 8959, Additional Medicare Tax
Frequently Asked Questions
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H1B TaxFile Team
Written by the H1B TaxFile editorial team — tax professionals and software engineers who specialize in U.S. federal tax filing for H-1B visa holders, F-1 students, and nonresident aliens.
Reviewed by a licensed CPA with international tax experience.
Disclaimer: This guide is for educational purposes only and does not constitute tax or legal advice. Tax laws are complex and change frequently. Consult a qualified tax professional for advice specific to your situation.