Contract & Interim — How We Work

How Our ContractModel Works

IR35 assessment process, contract-to-permanent mechanics, SOW vs day-rate structures, payment terms, and timeline — everything a hiring manager needs before picking up the phone.

IR35 Assessment

IR35 — What We Do, and Why It Matters

IR35 is the tax framework that determines whether a contractor is treated as a disguised employee or as genuinely self-employed. Since April 2021, the responsibility for making that determination sits with the end client — not the contractor. If the determination is wrong, the client and the fee payer (us, in a contract arrangement) bear the tax liability. We take this seriously.

We issue a written Status Determination Statement (SDS) on every engagement before work begins. This is not an internal checkbox — it is a formal document that both the client and the contractor receive, setting out the determination and the reasoning behind it. The assessment is carried out by a qualified IR35 specialist. We do not use automated tools as the sole basis for a determination on complex or borderline roles.

If you have used agencies that do not provide a written SDS, or where the IR35 status is set by the client alone without specialist input, you are carrying an unquantified compliance risk. We eliminate that risk before the engagement starts.

Written SDS on every engagement
Both parties receive a formal Status Determination Statement before the contractor starts. No exceptions.
Qualified specialist assessment
Not an automated tool. Complex or borderline roles are assessed by a qualified IR35 specialist with knowledge of buy-side working practices.
Reassessment if working practices change
If scope or working arrangements change materially mid-engagement, we reassess and issue a revised SDS before the new arrangement begins.
Rate differential — Inside vs Outside IR35
Inside IR35 gross day rates are typically 20–25% higher than Outside IR35 equivalents for the same net take-home. This is because Inside IR35 contractors pay employee NICs and income tax via PAYE or umbrella, rather than drawing dividends through a PSC. Rate benchmarks on our contract page are calibrated for Inside IR35 — Outside IR35 mandates are quoted per engagement based on scope and contractor seniority.
Contract-to-Permanent

Conversion — Commercial Mechanics

Contract roles frequently convert. We structure the commercial terms upfront so the conversion is clean and neither party is surprised by the fee at the point it happens.

Conversion fee agreed at brief stage
The conversion fee is structured on a percentage of first-year base salary, agreed in the engagement terms before the contract starts — not negotiated at the point of conversion. No surprises, no renegotiation when the contractor has already proven themselves. Specific terms quoted per engagement.
Timing is flexible
Conversion can happen at any point in the engagement — at the end of the initial term, at a renewal point, or early if both parties want to move faster. Early conversion pays the full agreed fee regardless of how far through the contract the conversion occurs.
Most PM Technologist and Python Quant Developer contracts convert to permanent within 6–9 months. KDB and C++ roles extend more often than they convert — the market for those skills at permanent level is tighter and the contractor premium is accepted long-term by most clients.
Engagement Structure

SOW vs Day-Rate — When Each Applies

The structure of the engagement affects IR35 status, invoicing, and how deliverables are defined. Most quant engineering contracts run as day-rate, but SOW is the right model in specific circumstances.

Day-Rate Engagement

Time-and-materials, client direction

The contractor is paid for time delivered — typically five days per week. The client directs the work on a daily basis and scope can flex. The contractor works within the client's team, follows the client's processes, and the engagement can run indefinitely until either party terminates.

Contractor embedded in client team
Client direction on daily work
Scope can evolve week to week
Inside IR35 more common
Timesheet-based weekly billing
Typical for KDB, Python, DevOps roles
The large majority of quant engineering contracts we place run on a day-rate basis. Most systematic hedge fund environments involve embedded working and daily client direction — even when the contractor is highly autonomous technically.
Statement of Work (SOW)

Outcome-based, contractor autonomy

Payment is tied to delivery of defined outputs — a platform migrated, a system built and handed over, a set of deliverables completed to specification. The contractor has meaningful autonomy over how and when they work, and the scope is fixed in writing at the start of the engagement.

Defined deliverables and acceptance criteria
Contractor controls how work is done
Fixed scope agreed in advance
Outside IR35 more readily supportable
Milestone or completion-based billing
Typical for migrations, platform builds
Examples where SOW is appropriate: KDB 3.x to 4.1 migrations with defined scope, cloud infrastructure build-outs with a delivery acceptance gate, MLOps platform stand-ups for a specific research team.
Timeline

From Enquiry to On Site

Typical timeline for a senior quant engineering contract role. The single biggest variable at every stage is client interview availability.

Day 0
Brief received
You describe the role, stack, IR35 expectation, start date and rate. We confirm whether it is in our specialism within 24 hours. If we cannot place it well, we say so.
Day 1–3
Shortlist returned
We work our active contractor network. Most KDB, C++ and Python quant dev searches produce a qualified shortlist within 48–72 hours. Shortlists are typically 3–5 candidates, all pre-screened for the specific tech stack and rate range.
Week 1–2
Interviews
We manage scheduling. For contract roles, a single technical interview round followed by a brief cultural conversation with the team lead is the norm. We do not support multi-stage interview processes for contract mandates — they slow placement and rarely improve outcomes.
Week 2
IR35 assessment and offer
IR35 determination completed, written SDS issued, rate finalised, terms agreed. Right-to-work verification and two professional references completed as standard on every contractor before engagement begins.
Week 4–8
Contractor on site
For most roles, 4–6 weeks from brief to on site. Specialist roles — Lead/Principal KDB, MLOps with finance domain, senior C++ — allow 6–8 weeks. If you need someone in 2 weeks, tell us at brief stage — it is sometimes possible with the right candidate already available.
FAQ

Questions Buyers Actually Ask

The questions a sophisticated hiring manager or procurement lead will want answered before they pick up the phone.

Ready to Discuss a Brief?

Tell us the role, stack, start date and rate. We confirm within 24 hours and return a qualified shortlist within 48–72 hours.