Utilize your financial knowledge, give your answer or opinion to the input question or subject . Answer format is not limited.

Should I be filling out form W-9 for somebody I sold used equipment to?
They are a business. You're not a corporation. They paid you more than $600 during the year, so they're supposed to send 1099 to you and the IRS about it. They need your taxpayer certification (W9) for that. They were supposed to ask for it before they paid you, but yes - they're supposed to ask for it.