X12 835 QTY01 (Quantity Qualifier Code): Format, Values, and Testing Notes
QTY02 is just a number — it is QTY01 that tells your system whether that number means covered days, non-covered days, or something else entirely. Get the qualifier wrong in a test fixture and your length-of-stay calculation will confidently produce a number that means nothing.
QTY01 is a two-character code that classifies the count carried in QTY02. In an 835, the qualifier most often distinguishes covered days from non-covered days on an institutional claim, though the code list supports other quantity types a payer might need to report at the claim level.
Common qualifier codes you will see in testing
Example
A synthetic QTY01 value of NA paired with a count of 2, reporting two non-covered days on the claim.
Where this trips people up
Test generators frequently hardcode QTY01 to CA because covered-day counts are the most common case, then never produce an NA or OU value — so the branch of code that handles non-covered days or generic units never runs until a real payer sends one. It is also easy to forget that QTY01 alone does not tell you which claim-level total it should reconcile against; that mapping lives in your own system's business rules, and synthetic files that only ever use one qualifier code will never surface a mapping bug.