A prescription or procedure can be ordered and still not happen for days. Prior authorization is a coverage review conducted before the service, and its steps account for the delay.
The requirement attaches to coverage, not care
Prior authorization does not determine whether a treatment is appropriate. It determines whether the plan will pay for it under the terms of that specific policy.
Clinicians may proceed without approval, but the patient then bears the cost, which is why practices generally wait for a determination.
Because requirements are set plan by plan, the same order can require review for one patient and none for another in the same clinic.
Criteria are compared against submitted documentation
Plans publish medical necessity criteria for reviewed services, typically drawn from clinical guidelines and specifying what must be documented.
Common criteria include a diagnosis within a defined set, evidence that alternatives were tried, or results from prior testing.
The review compares submitted records against those criteria, so an incomplete submission produces a denial that reflects missing paperwork rather than a clinical judgment.
Step therapy adds sequencing requirements
Some policies require that a lower-cost treatment be tried first, with the preferred option approved only if the first proves ineffective or unsuitable.
Exceptions exist where a prior trial already occurred or where the required drug is contraindicated, but those exceptions must themselves be documented and requested.
The sequencing is a coverage rule, and whether it fits a particular patient is a clinical question for the treating clinician to raise through the exception process.
Appeals run through defined levels
A denial can be appealed internally, and plans generally offer expedited review where a delay would jeopardize health.
Peer to peer review lets the prescribing clinician discuss the case directly with a reviewing physician, which can resolve disputes that documentation alone did not.
After internal appeals are exhausted, many plans are subject to external review by an independent entity, with rules that vary by plan type and state.
Automation is changing the timeline in both directions
Electronic submission connected to health records can return decisions far faster than fax-based workflows, and routine approvals may return almost immediately.
Automated screening also flags a larger share of requests for review, so faster processing does not automatically mean fewer requirements.
Rules governing response times and transparency vary by state and plan type and continue to change, so patients facing a delay should ask the plan for its current timelines and appeal rights.