Date of service
The date of service is the date a service was furnished, as reported on the claim. It anchors the filing clock, fixes which coverage rules and fee-schedule amounts apply, and for some services decides which entity is permitted to bill — and there is no single federal definition of it, only service-specific rules.
Updated
The date of service is the date on which a reported service was furnished to the patient. It is a required field on every claim, and it is the date almost every other rule on that claim is measured against: the filing period, the coverage policy in force, the fee schedule amount, the patient's eligibility and benefit year, and the version of a coding edit that applies.
There is no single, general federal definition of the term. Where the answer could be genuinely unclear — because the ordering, the collection of a specimen, the performance of a test and the reporting of a result can all fall on different dates — the rules define it for that specific service rather than in the abstract. Medicare's laboratory date-of-service rule at 42 CFR 414.510 is the clearest example: it exists because a laboratory service has several candidate dates and the choice between them changes who may bill.
In practice
Because the date of service is the anchor rather than a description, an error in it propagates. Medicare's filing limit at 42 CFR 424.44(a)(1) runs for one calendar year after the date of service for services furnished on or after 1 January 2010, so a mis-dated claim can consume its own filing window. The same field selects which published policy and which schedule amount govern, so a claim dated into the wrong period can be adjudicated correctly against the wrong rules.
Payer conventions add a second layer. Whether a payer measures its own filing period from the date of service or from some other event, and how it treats a service spanning more than one day, is a matter for that payer's published guidance and contract rather than something to generalize. The rule that does not vary is that the date reported should be the date the service was actually furnished, established by the record rather than by the billing calendar.
Commonly confused with
- Date of submission: The date of service is when the service was furnished; the date of submission is when the claim was transmitted. Filing limits are generally measured from the first and satisfied by the second, so the gap between them is the practice's working window rather than a formality.
- Date the specimen was collected: For most laboratory tests these are the same date, because Medicare's general rule makes the collection date the date of service. They come apart under the exceptions at 42 CFR 414.510(b), where the date of service can instead be the date collection ended, the date the test was performed, or the date an archived specimen was taken out of storage.
- Statement date: A statement date is when a bill was produced for the patient. It has no bearing on the date of service, on which rules applied, or on any filing period, and confusing the two is a common source of disputes about whether a charge is timely.