[jljmes5]

Show me proof that the IRS requires a SS# in order for a person to be paid for a patient human study participation, or honorarium?

[AK lawyer]

show me proof that the IRS requires a SS# in order for a person to be paid for a patient human study participation, or honorarium?

If the IRS requires an informational return (see the following), it requires the SS# of the person to whom the paymment was made.

... IRS instructions for form 1099, including a guide to what payments must be reported.
Examples of report amounts paid to independent contractors (in IRS terminology, such payments are nonemployee compensation). The ubiquity of the form has also led to use of the phrase "1099" to refer to contractors themselves. U.S. tax law requires businesses to submit a Form 1099 for every contractor paid at least $600 for services during a year.
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IRS tax forms - Wikipedia, the free encyclopedia