Does receiving a 1099 decide that a worker is an independent contractor?

No. The information return is evidence of how the business reported the payment, but it does not decide worker status. Federal classification depends on the relationship facts, especially the right to control what work is done and how it is done.

If the facts show employee-type control, the EA should evaluate whether the worker was misclassified. That may mean gathering documentation, considering Form SS-8 for a worker-status determination, and evaluating Form 8919 if the worker was treated as a contractor but should report employee Social Security and Medicare tax.