She's subject to US social security/SE tax unless she pays into Japan's system and the US and Japan have a totalization agreement.

Japanese taxes were withheld from her income. They are processing it in Japan I think. So would she have to file for SS taxes in US?

What kind of Japanese taxes did she pay?

Income?

Japan's equivalent of social security?

Both?

Something else?

The form just says Income Tax Withholding

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@jamessite wrote:

The company states that she worked as an independent contractor, NOT an employee. Can I put that amount of earnings on Line 19, or does it go on Line 20a of Form 2555?

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Line 19 is for wages (an employee).  As a contractor, it sounds like it belongs on 20a.  As a contractor, she is subject to Self-Employment tax. 

But before you do that, verify that your client qualifies for Form 2555, including that her "Abode" is in Japan.

As Susan said, you need to find out if your client is paying Social Security to Japan.  If she is, then see the information below to exclude SE tax on her US return.

"To establish that your self-employment income is subject only to foreign social security taxes and is exempt from U.S. self-employment tax, request a certificate of coverage from the appropriate agency of the foreign country. If the foreign country will not issue the certificate, you should request a statement that your income is not covered by the U.S. social security system from the U.S. Social Security Administration. Attach a photocopy of the certificate or statement to your Form 1040 each year you are exempt from U.S. self-employment tax. Also print "Exempt, see attached statement" on the line for self-employment tax."

https://www.irs.gov/individuals/international-taxpayers/self-employment-tax-for-businesses-abroad