Form 5472
For each foreign owner that has 25% or more ownership a US business entity must file form 5472. This form contains basic information about the owner such as his or her full name, country of citizenship and address as well as a summary of all transactions between the business and the owner. This is an informational form and does not result in an additional tax, however information in it may be used for audit purposes.
For corporations, partnerships including multi-member LLCs this form is attached to the main tax return forms and can be filed electronically. For foreign owned single-member LLCs 5472 must be mailed to:
Internal Revenue Service
1973 Rulon White Blvd M/S 6112
Attn: PIN Unit Ogden, UT 84201
or faxed to 855-887-7737
In order for the form to be accepted, it must be attached to pro forma 1120 form. The following instructions are for foreign owned single-member LLCs only.
access form 1120 at https://www.irs.gov/pub/irs-pdf/f1120.pdf (make sure it's the current year's edition)
across the top of the form write: Foreign-owned U.S. DE (print if possible)
enter the name of the corporation, address EIN, and choose one of the options in E
sign and date on the bottom
do not enter any other information on form 1120
access form 5472 at https://www.irs.gov/pub/irs-pdf/f5472.pdf
while it's a good idea to have a professional do it for you, if you only had a handful transactions you may try to do it yourself.
mail or fax 1120 and 5472 to the address / number mentioned above.