Oncology billing is unlike any other specialty in medicine. Drug costs represent 60 to 80% of total revenue. A single incorrect J-code unit calculation or missing NDC number on a $40,000 chemotherapy claim costs more than a week of average medical office revenue. Add prior authorization battles for immunotherapy, 340B compliance requirements, clinical trial billing rules, and step therapy denials — and you have a billing environment where errors are expensive, fast, and easy to make. This guide covers J-code billing, buy-and-bill, 340B, clinical trial compliance, step therapy appeals, and the workflows that help Qualigenix clients achieve a 99% claim accuracy rate, 95% first-pass acceptance, and a 30% reduction in AR days.