A Status Determination Statement (SDS) is the formal document a medium or large private sector client must produce explaining whether a contractor engagement falls inside or outside IR35. This guide explains what a valid SDS should contain in 2026/27 and what happens if it is missing or defective.
What an SDS Must Contain
A Status Determination Statement must state the client’s conclusion on whether the engagement is inside or outside IR35, and set out the reasons for that conclusion, rather than simply stating the outcome without any supporting explanation of how it was reached.
It must be passed to both the contractor and, where there is one, the agency or other party the client contracts with directly, and each party further down the chain must in turn pass the SDS on to the next party until it reaches whoever actually pays the contractor’s company.
The Reasonable Care Standard
Clients are required to take "reasonable care" when reaching a status determination, meaning a genuine, considered assessment of the actual working arrangements — using an appropriate tool or process and looking at the real substance of the engagement — rather than a blanket, generic determination applied to every contractor regardless of their individual circumstances.
Failing to take reasonable care can mean the client itself becomes liable for any resulting unpaid tax and National Insurance, rather than the liability sitting further down the chain with the fee-payer, so clients have a strong incentive to get this right rather than treat it as a formality.
The Disagreement Process and an Invalid SDS
If a contractor disagrees with the determination, the client must operate a status disagreement process, considering the contractor’s representations and responding within a set timeframe with either a revised determination or a reasoned explanation for maintaining the original decision.
If no valid SDS is provided at all, or it is not passed correctly down the contractual chain, the client can become responsible for the tax that should have been correctly assessed and deducted, similar to the consequence of failing to take reasonable care in the first place.
Frequently Asked Questions
What must a valid Status Determination Statement include?
It must state the client’s conclusion on whether the engagement is inside or outside IR35 and explain the reasons for that conclusion, based on a genuine assessment of the actual working arrangements rather than a blanket statement with no reasoning provided.
What does "reasonable care" mean for a client making a status determination?
It means the client has genuinely considered the real working practices of the specific engagement, using an appropriate assessment method, rather than applying the same generic determination to every contractor regardless of how their arrangement actually operates.
What happens if my client does not give me an SDS at all?
If no valid SDS is provided, the client can become liable for the tax that should have been correctly assessed and collected, effectively as though reasonable care had not been taken, since the SDS is a mandatory part of the process.
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Can I challenge a Status Determination Statement I disagree with?
Yes — clients must operate a status disagreement process allowing you to set out why you disagree, and they must respond within a set timeframe, either revising the determination or explaining why the original decision is being maintained.
Who is liable if the client fails to take reasonable care?
The client itself can become liable for the resulting unpaid tax and National Insurance, rather than the liability automatically passing to the fee-payer or agency further down the contractual chain, which is a key incentive for clients to get the assessment right.
Does the SDS need to be passed to every party in a contractual chain?
Yes — each party in the chain, from the end client through any agencies to the fee-payer, is required to pass the SDS on to the next party, and a break in this chain can itself create liability for whichever party failed to pass it on correctly.
Can a single blanket determination cover all my contracts with a client?
No — a determination must relate to the specific engagement it covers, so a client cannot simply issue one generic "inside IR35" statement for every contractor without looking at each individual working arrangement; doing so is a common reason an SDS fails the reasonable care standard.
How long does a client have to respond under the status disagreement process?
A client must respond to a disagreement within 45 days of receiving it, either confirming the original determination with reasons or issuing a new one, and the original SDS remains in effect for tax purposes until that response is given.
Do small companies also have to issue a Status Determination Statement?
No — the SDS obligation applies only to medium and large private sector clients as defined by the Companies Act size thresholds; clients who qualify as small are exempt, and in that case the contractor’s own company remains responsible for determining status.
Should I keep a copy of every SDS I receive?
Yes — it is sensible to keep a record of each SDS you are given, together with any reasons provided, since this evidence can be important if a status dispute arises later or if HMRC queries the determination for a particular engagement.
Disclaimer: This guide reflects UK rules as they generally apply in 2026/27. This guide is for general information only and is not professional advice. Consult a qualified adviser and refer to gov.uk for current official guidance before relying on any treatment.
