As a tax professional you are gathering all the information that the tax payer is providing and hopefully you have an application or agreement form that they signed stating all information they are providing is true......that statement right there would dissolve you from any false information they provided. They will have to deal with the audit and fraud department for false documents.

I would ask for the same document requirements that the IRS would ask for the credit....SS for the provider, full name, address etc. if they are not willing to provide the documents let them know you will not be able to submit the credit. It's better to lose a client that you feel is not being honest than to ruin your prepares status for filing false returns.

I hope this helps! Good luck!