C contract jobs: rates and IR35
A C contractor is hired for a fixed term, almost always against a day rate rather than a salary. The work is embedded systems, performance-sensitive services and code that sits close to the hardware. This page is the market around that skill: who hires, what the day rate looks like, how IR35 tends to fall, and the live contracts on IR35 Jobs.
Updated 1 November 20264 min read
What a C contract is
A C contractor is hired for a fixed term, almost always against a day rate rather than a salary. Clients hire for embedded systems, performance-sensitive services and code that sits close to the hardware. The contract is usually three to six months with an extension if the work continues, and the advert should say whether it is outside IR35, inside IR35, or silent. Silent is common, and it is not the same thing as outside.
The title in the advert is often looser than the skill. A role tagged C on this board matched the skill in the title or the spec, which is a better filter than a job board's own category. Open the C board for the current list rather than a recycled write-up.
Who is hiring
Banks, product companies, consultancies and the public-sector programmes that still build their own software are the clients behind most C adverts. Agencies still post the majority of contract roles in the UK, so the name on the row is often the recruiter, not the end client. The skill and the IR35 line tell you more than the agency brand.
Demand moves with programmes, not with the calendar. A quiet week on C is not a dead market. New contracts are added every hour, and the ones from the last 48 hours are visible to members first because that is when they get filled.
C day rates
Advertised C day rates commonly sit between £450 and £750. That is the headline number, before tax, umbrella margin or the costs of a limited company. Work clusters in London, Manchester, Edinburgh, Bristol and remote. The rate on a specific advert is on the board when the recruiter published one. Where they wrote "competitive" instead, the role is harder to compare and usually not in a hurry to tell you.
A higher inside IR35 rate can be worth less than a lower outside one. Run both numbers before you negotiate, and read the C day rate guide for how to compare them. Benchmarks across skills are on UK contractor day rates.
IR35 on these contracts
Outside IR35 is common on C delivery contracts, particularly where you use your own equipment, control your own method and can send a substitute. Staff-augmentation inside a bank or a government department is still frequently marked inside, sometimes as a blanket decision. Read the status on the advert and then read the working practices, because the two do not always agree.
C outside IR35 jobs collects the point in one place. The live filter is outside IR35 jobs across every skill, and inside IR35 jobs for the other column. We report the status the advert states. We do not decide it, and neither does a keyword.
Where the work is
C contracts turn up most often in London, Manchester, Edinburgh, Bristol and remote. A city on the advert is not always a daily commute. Hybrid is the default pitch, and a role marked remote should say so rather than implying it.
Use the board's location and radius filters once you are a member. Free browsing shows the delayed board. The link through to the original advert, on every C job, is part of membership and the 14-day pass.
Live roles on the board
These C contracts are on the board now. The day rate and IR35 status are public. The link to the original advert is for members.
- Systems: Senior Linux Infrastructure Engineer (London) (D994AC1) — London
- Contract Embedded Software Engineer — Normanton, West Yorkshire, £50-£60/hour
- Systems: Senior Linux Infrastructure Engineer (London) (84BEB02) — London
- Senior Linux & Python Infrastructure Engineer — Glasgow, Lanarkshire, £450-£550/day Inside
- Scientific Software Engineer - Research Platforms — London, £1,000-£1,100/day Inside
- Data Analyst (Mobile Backhaul) — London, £350-£400/day Inside
- Data Analyst/Technical BA/Data Governance — Ireland, £460-£485/day
- Solution Architect - Data Platforms — London, £800/day Inside
See live C contracts · Membership unlocks apply links and the first 48 hours