correctiions for wrong codes

Is there a way to re-bill or send in a correction if the wrong cpt code was billed out? For example if the cpt code for total T4 was billed but a free T4 was performed? If reimbursement has been received already can you go back to correct? Thank you.

Only if you want to pay

You can always send the insurance a corrected claim, with a corrected claim sheet to indicate you are "Replacing" the previous billed claim. Keep in mind, they will ask for their money back once they determine that an overpayment was made.