When a shift opens up, most facilities reach for overtime first. It feels cheaper — no agency markup, no new faces on the unit. But "cheaper" only holds if you stop counting at this week's payroll. Run the full comparison and the picture changes.
The visible math
Overtime hours are paid at a premium — time-and-a-half under federal law for hours past 40. So the direct comparison is:
- Overtime hour: your nurse's wage × 1.5, plus the payroll taxes on it
- Agency hour: the bill rate, which bundles wages, taxes, insurance, and the agency's services
On that math alone, the two are often closer than people expect, especially for senior staff whose overtime rate is high. But the visible math isn't the real story.
The invisible costs of leaning on overtime
Turnover. Nurses consistently rank forced overtime among the top reasons they leave a job. Replacing a nurse is enormously expensive once you count recruiting, onboarding, lost productivity, and the agency or overtime coverage you'll need during the vacancy. If routine mandatory overtime pushes even one or two nurses out per year, it erases years of "savings."
Fatigue and safety. Tired clinicians make more errors. That's a patient-safety issue first, and a liability issue close behind.
The death spiral. Overtime causes burnout, burnout causes callouts and resignations, which cause more overtime. Facilities that rely on mandatory overtime as a system — not an occasional tool — tend to find the holes getting bigger, not smaller.
Where each tool actually belongs
- Overtime is fine as a voluntary, occasional tool — staff who want extra hours picking up an open shift now and then.
- Agency per diem is built for the unpredictable gaps: sick calls, census spikes, the shifts nobody volunteers for.
- Agency contracts are built for the predictable gaps — leaves, seasonal swings, vacancies under recruitment — so those never hit the overtime budget at all.
The healthiest staffing models we see use all three deliberately, and mandate overtime almost never.
Run your own numbers
Take last quarter's overtime hours. Split them into "predictable gap" hours (leaves, known vacancies) and "surprise" hours. Price the predictable portion as a contract placement and the surprises as per diem, then weigh that against the overtime premium you paid — plus an honest estimate of what burnout-driven turnover costs you per departure.
If you'd like help running that comparison with real rates for your roles and market, Interim HealthCare Staffing of Minneapolis will do it with you, no obligation. Call (612) 444-JOBS or request staff online.
Frequently asked questions
Is a staffing agency cheaper than overtime?
On a per-hour basis, agency and overtime costs are often closer than expected — especially for senior nurses with high base wages. But the real comparison includes the hidden costs of mandatory overtime: nurse burnout, turnover, and the expensive recruiting and coverage gap that follows each resignation. For many facilities, strategic agency use is the lower total cost.
What are the hidden costs of mandatory overtime for nurses?
The most significant hidden costs are nurse turnover (replacing a nurse costs tens of thousands of dollars when recruiting, onboarding, and productivity loss are included), patient safety risk from fatigued staff, and the compounding effect — overtime causes burnout, burnout causes callouts and resignations, which cause more overtime.
When should a facility use overtime instead of a staffing agency?
Overtime works best as a voluntary, occasional tool — for nurses who want extra hours and pick up a shift willingly. Agency per diem handles the unpredictable gaps; agency contracts handle predictable gaps like leaves and seasonal swings. The most sustainable facilities use all three deliberately and mandate overtime rarely.