Billing, Claims Submission, and Reimbursement
Claim forms and core data
Use the CMS-1500 (837P) for professional claims and the UB-04 (837I) for institutional claims. Critical fields include the insurance type, the insured's ID, the patient's relationship to the subscriber, diagnosis pointers on each service line, CPT or HCPCS with modifiers, charges, units, place of service, and the billing provider NPI. Incorrect pointers and NPI errors are common, inexpensive-to-prevent denials.
Clean claims and timely filing
Scrub every claim before release: demographics, eligibility, authorization on file, code-edit pairs, and NDC for drug claims. Timely filing generally runs from the date of service, but a secondary claim is often measured from the primary payer's EOB date. Read each payer's policy rather than assuming a uniform window.
Adjudication and reimbursement
An ERA/835 posts electronically; the EOB shows the allowed amount, the contractual adjustment, the payer payment, and patient responsibility. Allowed amount minus contractual adjustment = payer payment plus patient cost-sharing (deductible, coinsurance, copay). Do not bill the patient before adjudication unless the encounter is self-pay or a valid ABN applies, and never balance bill beyond cost-sharing for in-network Medicare or Medicaid services.
Appeals
Medicare appeals move through redetermination, reconsideration, ALJ, Medicare Appeals Council, then federal court. Commercial plans set their own levels and deadlines.
Worked example
Allowed amount $2,000, deductible already met, 80/20 coinsurance: the payer remits $1,600 and the patient owes $320. Post the $320 to patient responsibility, not to contractual adjustment.
Traps
Writing off patient responsibility as an adjustment. Missing the appeal filing deadline. Failing to attach the primary EOB to a secondary claim.