SDS (Status Determination Statement)
A written IR35 status decision issued by a medium/large end client — stating inside or outside IR35 with reasons.
A Status Determination Statement (SDS) is a written document that a medium or large end client must issue to a contractor (and pass down the supply chain to the agency) stating whether the engagement is inside or outside IR35.
An SDS is required under the off-payroll working rules (Chapter 10 ITEPA 2003) for all engagements with medium/large private sector or public sector clients where the contractor uses a limited company or similar intermediary.
The SDS must include the determination (inside or outside) and the reasons for the decision — not just the conclusion. A bare determination without reasons is not a valid SDS.
If you disagree with an SDS, you can formally dispute it. The client must respond within 45 days with either a revised SDS or a maintained determination with further reasoning. If they fail to respond in time, the tax liability transfers back to the client.