A W-9 is the form an independent contractor gives a business to provide their taxpayer ID for 1099 reporting. A W-4 is the form an employee gives their employer to determine how much income tax to withhold from each paycheck.
The two forms map directly onto worker classification: a 1099 contractor fills out a W-9 and receives payments with no tax withheld, while a W-2 employee fills out a W-4 and has income tax withheld from every paycheck based on the elections made on that form.
Collecting the right form at the start of a working relationship, before the first payment goes out, avoids a scramble later at tax time. A company that pays a contractor without ever collecting a W-9 can struggle to issue an accurate 1099-NEC when the filing deadline arrives.
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