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What to Do if a Vendor Checks Box 3B on a W-9 Form
October 30, 2025
Q. What additional information do I need to ask a vendor if they check Box 3B on a W9?
A.
(Answered by IOFM's third-party tax expert)
The true goal on the IRS side with box 3b is for partnerships. If your business is a partnership, you should get W-9s from your partners. If a partner provides you with a W-9 with box 3b checked, you'll need to consult with whoever prepares the partnership tax return, as there are implications with that (filings called Schedule K-2 and Schedule K-3).In other…
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