Contract-to-hire is the lowest-risk way to make a senior engineering hire. You watch someone work in your codebase for three to six months before committing to a permanent offer — no interview process comes close to that signal. It's also the offer most likely to be declined by exactly the people you want.
Both facts are true, and the gap between them is where employers get this wrong.
TL;DR
- The signal is unmatched. Months of real work in your systems beats any interview loop.
- The pool is smaller. Many strong senior developers decline contract-to-hire outright — they want security and benefits from day one, and they have options.
- Conversion fees run 15–25% of first-year salary through a staffing partner, usually stepping down to zero after 6–12 months on contract.
- Agree conversion terms at signature. Negotiating when you already know you want the person is negotiating from zero leverage.
- It works best when the contract period is genuinely evaluation in both directions, and fails when it's a permanent role with a probation period bolted on.
Where contract-to-hire genuinely beats a permanent offer
You've seen the work. Not a take-home, not a system-design conversation — actual delivery in your codebase, under your process, with your ambiguity. Mis-hire rates on senior engineers are high precisely because interviews measure interview performance. Three months measures the job.
It de-risks a first senior hire. If this is the first staff-level engineer in a small team, the cost of getting it wrong is disproportionate. Contract-to-hire caps that exposure.
It works around a frozen req. Bring someone in now on project budget, convert when headcount reopens. This is the most common legitimate use — see hiring developers during a hiring freeze.
Both sides get to leave. Underrated. A senior engineer who discovers the architecture is worse than described can walk without a resignation on their record, and you can end an engagement without a performance process.
Why strong candidates say no
Worth stating plainly, because employers consistently underestimate it.
A senior developer with options is comparing your contract-to-hire offer against permanent offers with equity, health cover from day one, and no ambiguity. Your offer asks them to carry risk for three to six months in exchange for a possibility. Many will decline, and they're being rational.
The specific objections:
- Benefits gap. In the US especially, health coverage during the contract period is a real cost the candidate absorbs.
- The conversion is not guaranteed and they know it. "We intend to convert" is a statement about your intentions, not about next quarter's budget.
- They've been burned. Contract-to-hire has a reputation, earned by companies that extended indefinitely and never converted.
- Compensation is usually flat. Contract rate rarely reflects the risk premium the arrangement actually carries.
What changes the answer: a written conversion trigger ("conversion offer at month four subject to satisfactory delivery, at a base of £X"), a contract rate that acknowledges the missing benefits, and honesty about what could stop it.
The conversion fee, and when to negotiate it
If you're hiring through a staffing partner, converting a contractor to permanent carries a fee. Typical structure:
| Time on contract before conversion | Typical fee |
|---|---|
| 0–3 months | 20–25% of first-year salary |
| 3–6 months | 12–20% |
| 6–12 months | 5–12% |
| 12+ months | Often zero |
The logic is that the partner's placement cost amortises across the contract margin they've already earned. The step-down is normal and negotiable.
Negotiate it at contract signature. This is the single most valuable line in this article. At signature, the partner wants the engagement and you have alternatives. At month four, when you've decided this is the person you want and they're already embedded in your team, you have none. The fee you agree in those two moments differs by a lot.
Ask specifically for: the step-down schedule in writing, what happens if the contractor is extended rather than converted, and whether the fee is calculated on base or total compensation.
Structuring the contract period
Three to six months. Under three, ramp consumes the evaluation window and you're judging someone on their onboarding. Past six, you've stopped evaluating and started avoiding a decision — and the candidate knows it.
Define what "satisfactory" means before day one. Not a formal scorecard, but a written answer to "what would make this an obvious yes at month four?" Two or three delivery outcomes and a note on collaboration. Without it, conversion becomes a vibe, and vibes favour whoever is loudest.
Schedule the decision. Put the conversion conversation in the calendar at the start. Drifting past it is the most common failure mode and it's the one that damages your reputation with candidates — they notice, and they tell people.
Keep the work real. Contract-to-hire evaluated on a side project measures nothing. Put them on the actual roadmap, with the actual ambiguity.
Where it goes wrong
- Indefinite extension. Six months becomes eighteen. At that point you have a permanent employee without benefits, an unhappy one, and a lot of goodwill spent.
- Using it to avoid a hiring decision. If you'd hire them permanently today, do that. Contract-to-hire is for genuine uncertainty, not for deferring conviction.
- No conversion budget. Starting a contract-to-hire with no realistic path to a req is a slow way to lose someone good and earn a bad reference.
- Different standards at conversion. Applying a full permanent interview loop at month four, after months of delivery, reads as bad faith. You already have better evidence than the loop would produce.
Contract-to-hire vs the alternatives
| Approach | Signal quality | Candidate pool | Speed to start | Best when |
|---|---|---|---|---|
| Permanent hire | Interview only | Largest | 6–12 weeks | The role is definitely permanent and funded |
| Contract-to-hire | Months of real work | Smaller | 1–2 weeks | Genuine uncertainty, or a frozen req |
| Straight contract | Months of real work | Large | 1–2 weeks | Defined project with an end date |
| Trial project (paid) | One piece of work | Moderate | Days | Testing a specific skill quickly |
If you're certain the role is permanent and funded, hire permanently — you'll get a better field. Contract-to-hire earns its place when the uncertainty is real.
FAQ
What is a typical contract-to-hire conversion fee? 15–25% of first-year salary through a staffing partner, stepping down the longer the contractor works before converting, and often reaching zero after 12 months. Agree the schedule at signature rather than at conversion.
How long should a contract-to-hire period be for a senior developer? Three to six months. Shorter and you're evaluating onboarding rather than delivery; longer and you're deferring a decision you already have the evidence to make.
Do senior developers accept contract-to-hire? Some do, particularly those who prefer contract work or find the scope compelling. Many decline because they want benefits and security from day one. Expect a smaller field, and improve your odds with a written conversion trigger and a rate that acknowledges the risk.
Should the contract rate be higher than the eventual salary equivalent? Yes. The contractor carries the benefits gap and the conversion risk. A rate that maps exactly to the target salary asks them to take on risk for free, which is why offers structured that way get declined.
Can we run a full interview loop before converting? You can, but it signals that months of delivery told you nothing — which is either untrue or an indictment of your evaluation. Better to define the conversion criteria up front and assess against those.
What if we can't convert because the freeze hasn't lifted? Say so early and directly, and either extend on honest terms or help them land elsewhere. Silence past a promised decision date is what gives contract-to-hire its reputation.
Considering contract-to-hire for a senior role? First Bridge Consulting places contract engineers with conversion terms agreed at signature — including the step-down schedule in writing, so converting later doesn't cost you leverage. Get a staffing proposal in 48 hours →
Related reading: Hire Developers During a Hiring Freeze · Senior Engineer Interview Rubric · Contract Staffing services