Claims issues

We have 4 providers in our pediatric office in Texas and we bill under one provider.  Our BCBS claims are processing as specialist when patients see one of our nurse practitioners.  Everyone we have talked to with BCBS has told us something different and we are just at a loss as how to fix the issue.  This is cutting into our payments and getting worse by the day.  Two different Reps told us that the billing and rendering NPI where the same.  When we verify the insurance under our nurse practitioners they are pulling up specialist copay's though.  This makes me feel like it is an issue possibly with BCBS or credentialing, or maybe even with our Office Practicum pulling something we are not able to see to our clearing house.  When we called BCBS they told us that something on our claim form (that we cant see) is throwing an 81 which processes the claims on BCBS end as a specialist.  It is an 81 code for a LPN, we do not have specialists here at the office and no where in our system is information about LPN's.   Can anybody help with this?  Does anyone know if BCBS needs a group taxonomy code on claim forms?  BCBS like all other insurance companies cannot tell us what needs to be on the claim form.  Thank you!

Types of providers and billing

There is a difference in provider types, For NPs who work in restricted states, they cannot prescribe, diagnose, or treat patients without physician oversight, and are generally paid at a different rate.  However, it sounds like you are billing correctly, generally, NPs get paid at 85%, unless billed under the physician, they should then get 100%. There may be differences in your state or with the contacts start by looking up the provider's policy to see what BCBS rules are when billing for an NP? 
Examples of Taxonomy codes:

Pediatrics Taxonomy Code 208000000X
Nurse Practitioner (Pediatrics) Taxonomy coded 363LP0200X

Issues with Credentialling
Also, consider some BSBS rules re: "if network participation is available for a provider type, then that provider type is required to file claims under their own provider number. Services should not be billed under a supervising provider." 
If network participation is available for a provider type, then that provider type is required to file claims under their own provider number. Services should not be billed under a supervising provider. 
Taxonomy Numbers
When a provider applies for an NPI each provider assigns themselves a taxonomy number or two or three. Providers are asked to choose a taxonomy code that most closely describes their provider type, classification, or specialization. Sometimes the providers may not all match. In addition, find out what constitutes a specialist with the payer.  Is the same taxonomy number used on the payer's contract? Verify to ensure everyone is on the same page. 
Once you see how they are contracted, contact your provider rep to ensure your providers are set up correctly in the BCBS system, I have had this issue in the past and they (the payer) had it incorrect, which was affecting the provider's reimbursement.   
You can use this tool (URL below) to see what taxonomy number is assigned to the NPI #. Do your providers have something different than what they are contracted with?  
Here is the tool to help with that, (note, I am not sure if all taxonomies will show up on this list) but you can start here.https://npidb.org/taxonomy/208000000X/
BC Provider Representitave
Contact the provider representative assigned to your provider (NOT claims), provider reps are generally assigned by location and are there to help your provider with any issues you may have. You may need to see a copy of each provider's contract with BCBS and verify they are all mapping correctly, (the contract may also indicate how to bill under a supervising physician according to the contract.)  NPI-Taxonomy-Contract, they all need to be the same.  
As you can see there are several reasons your reimbursement may be different than what you are expecting, the above suggestions are common reasons for the difference in reimbursement for provider types.