United Nation does not have a EFIN number. I have client filing tax return (US citizen) can I file electronically

I presume you mean EIN.

If they are withholding social security they do have an EIN. How else would they submit it to the IRS?

Are you sure those are withholdings and not tax advance or reimbursement for 50% of SE-tax since UN withholds neither income tax nor FICA?

The starting point for advising this client should be reading this 35-page pdf publication from the UN:

https://www.un.org/Depts/oppba/accounts/tax/pubs/sticlatest.pdf 

Some of its more significant content:

“United Nations emoluments are considered wages or earnings from employment, and must be reported as such on line 1 of IRS form 1040, “Wages, salaries, tips, etc.”. United Nations earnings are not business income and should not be reported on IRS schedule C.

“United States citizens working for the United Nations and serving in the United States are taxed on United Nations earnings for Social Security contribution purposes as if they were self-employed. Their Social Security contribution on the gross amount of United Nations taxable income for 2019 must be calculated using IRS schedule SE (self-employment tax). This does not imply, however, that United Nations emoluments should be reported as business income on IRS schedule C.”

I wouldn’t get too hung up on trying to pound this square peg into the round hole of IRS electronic filing.

fwow, I just checked the paperwork and spoke w/ tp.

He received a 1 page form from UN. 2019 Statement of Taxable Earnings.

There's one amount; Daily Gross; subtotal and total are the same. . There is an * that says report on line 1 (but then the old form said report on line 7 which didn't work either...) There is no reference to FICA, SSN or State withholding tax.

If you received similar form I'd suggest filing as I outlined. My client said the UN generally pays the federal tax directly and sends him a check for the state tax due. He hasn't received it yet, but he said that they haven't complained yet either.... Last year, I filed w/ the 199a and they were pretty quick to whine that they we should amend without it.

UN is a PITA. Good luck

I ran across this same problem.  The UN does have an EIN number.  You just have to enter it as a W2.  That's the only way to do it.  The EIN for the UN is 90-0137550

Report UN taxable earnings (total amount from Statement of Taxable Earnings) on Line 1a, page 1 of IRS Form 1040.