Typically, the rendering providers Tax ID does not go on a claim form. The billing providers Tax ID goes on the claim form. For this reason, we tend to believe they may be referring to something else missing on the claim. For example, if the rendering provider is not listed on the EDI claim, this may be the resulting EDI rejection message from this payer.
Because this rejection message is rare and does not really make sense (the rendering providers Tax ID does not belong on a claim), it might be best to call the payer to find out why they are rejecting your claim.
IMPORTANT: When calling the payer, make sure to let them know that the claim was EDI rejected. Usually, when you call, the first person you talk to is in the payers adjudication department. These people can only see claims that made it past EDI (were not EDI rejected). You may ask to talk to their EDI department or whoever handles EDI rejections. They will have a record of the rejection.