From the UserTesting website: We do not send out 1099-MISC's to participants, as we pay you through PayPal, a third-party payment provider (see 1099-MISC Exemptions section here). You are still, as always, responsible for reporting all earned income and should consult a tax professional for any tax advice. Here is more information regarding PayPal's reporting requirements, and here is more information from the IRS about reporting miscellaneous income.
