Glossary
Supervision, Direction and Control (SDC)
The client's right to direct how, when, and where you work — high SDC is strong evidence of inside IR35.
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Supervision, Direction and Control (SDC) describes the level of control a client has over how a contractor performs their work — methodology, hours, location, sequence, who they collaborate with.
High SDC is a hallmark of employment. A genuine outside-IR35 contractor decides their own approach, hours, and methods within the deliverable's scope.
SDC is used both in IR35 case law and in the agency rules (Chapter 8 ITEPA) to determine whether someone should be taxed as an employee.
Related terms
- IR35 — The UK's off-payroll working rules — they decide whether a contractor should be taxed as a deemed employee.
- Inside IR35 — An engagement that falls within IR35 — the contractor is taxed as a deemed employee.
- Mutuality of obligation (MOO) — An employment-style commitment: the client must offer work, and you must accept it.
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