Date of service is the service date used in claims adjudication. It marks when treatment happened, not when billing or intake was completed.
Why it matters
Claims systems validate timeline windows, prior authorization rules, and payment cycles against this date. A mismatch with provider documentation is a common source of denied claims.
Claims mechanics
- DOS can differ from appointment date or date of service entry.
- The date determines what benefit year and plan rules apply.
- Retroactive service corrections often require amendment and resubmission.
Practical example
If a procedure is performed on March 1 but invoiced on March 10, reimbursement should align with the March 1 date for network and utilization rules.