Building an EOB Parser: Why Healthcare Documents Are the Hardest to Parse

I've built document parsers for tax forms, bank statements, and invoices. None of them prepared me for Explanation of Benefits documents. EOBs are the documents your health insurance sends after a medical visit. They explain what was billed, what insurance paid, and what you owe. Simple concept. Absolute nightmare to parse. Here's why - and how we eventually cracked it. The Problem with EOBs Every insurance company formats EOBs differently. Not just "slightly different layouts" - completely different information hierarchies, terminology, and structures. Blue Cross puts the patient responsibility at the top. Aetna buries it in a table on page 2. UnitedHealthcare uses cryptic codes that require a separate decoder ring. Kaiser somehow makes it even more confusing. And that's just the major payers. There are 900+ health insurance companies in the US, each with their own EOB format. Why Traditional OCR Fails We tried Tesseract. It read the text fine but had no concept of what the text meant