In the instructions section of IRS Form W-9 there is a “Specific Instructions” paragraph that provides guidance to LLCs with more than one member. Line 1 is mandatory. Line 2 is optional.
You must enter one of the following on this line; do not leave this line blank. The name should match the name on your tax return.
c. Partnership, LLC that is not a single-member LLC, C Corporation, or S Corporation. Enter the entity’s name as shown on the entity’s tax return on line 1 and any business, trade, or DBA name on line 2.
If you have a business name, trade name, DBA name, or disregarded entity name, you may enter it on line 2.
See our blog article on Disregarded Entities for more information on LLCs with only one member.