Hi,
I am H1B - resident alien.
I will be filing my 2015 tax with my wife as 'Married - Jointly'
According to IRS doc the limit for 'Married-filing jointly' is 250K but my employer has deducted 'Additional Medicare Taxes' based on 'Single-filing' limit.
My overall wages for 2015 is less than 250K so I hope I can refund my 'additional medicare taxes'. Kindly let me know how to do that...

https://www.irs.gov/Businesses/Small-Businesses-&-Self-Employed/Questions-and-Answers-for-the-Additional-Medicare-Tax


Thanks

The "Questions and Answers" has the answer to your question. See Number 14:

14. If my employer withholds Additional Medicare Tax from my wages in excess of $200,000, but I won't owe the tax because my spouse and I file a joint return and we won't meet the $250,000 threshold for joint filers, can I ask my employer to stop withholding Additional Medicare Tax?
No. Your employer must withhold Additional Medicare Tax on wages it pays to you in excess of $200,000 in a calendar year. Your employer cannot honor a request to cease withholding Additional Medicare Tax if it is required to withhold it. You will claim credit for any withheld Additional Medicare Tax against the total tax liability shown on your individual income tax return (Form 1040).

Thanks for the info.
Can you tell me how to claim credit in 1040 ?
Should I put the withheld tax amount in Line-10 of 1040 ? Or should I need to submit separate Form for this ?

The calculations for the Additional Medicare Tax are done on Form 8959, to include any refund due.

If you find this form unfamiliar, you should use a tax pro.

If you want my professional help, please email me at the email address in my profile.