X12 834 DTP01 (Date/Time Qualifier): Format, Values, and Testing Notes
One three-digit code decides whether the date that follows means a member's coverage is starting or stopping.
DTP01 is the qualifier that tells a downstream system what a given DTP occurrence's date actually represents. On an 834 enrollment file, the two qualifiers that matter most for coverage status are the coverage-begins date and the coverage-ends date, though the same segment shape can carry other date types depending on the loop.
Valid code values
Example
In this synthetic segment, DTP01=349 marks the date that follows as a coverage-ends date, with the member's coverage terminating on 2026-12-31.
Where this trips people up
It's easy to build test data that only ever includes a 348 coverage-begins qualifier, since that's the minimum needed to enroll a synthetic member. But a termination file needs a 349, and some carriers send both qualifiers on the same member loop at once — an addition with a future termination already scheduled. If your ingestion logic assumes there's exactly one DTP per member and grabs whichever one it finds first, it will misread a termination as an effective date or drop the termination entirely. Test with 348 alone, 349 alone, and both together in the same loop.