IR35 Defence Contractor Agreement Template UK
Working through a Personal Service Company in the defence sector exposes contractors to significant IR35 risk, particularly following the 2021 off-payroll working reforms under Chapter 10 of ITEPA 2003, which shifted status determination responsibility to medium and large client organisations. Without a robust, carefully drafted contract, HMRC can challenge your outside-IR35 status, triggering substantial backdated tax and National Insurance liabilities. A well-structured IR35 defence contractor agreement documents the true commercial reality of your engagement — demonstrating substitution rights, lack of mutuality of obligation, and genuine financial risk — providing a critical line of defence during any HMRC enquiry. Defence sector engagements carry additional complexity due to security clearance requirements and MOD supply chain regulations, making specialist contractual language essential. Protect your outside-IR35 position and generate a compliant, tailored agreement now.
Generate your IR35 Agreement free →Key clauses in a IR35 Agreement
Right of Substitution
This clause grants the contractor's PSC the genuine, unfettered right to substitute a suitably qualified individual to perform the services without requiring the client's approval based solely on personal preference. Under HMRC's IR35 assessment framework derived from ITEPA 2003, a credible substitution right is one of the strongest indicators of self-employment and outside-IR35 status, and its absence is routinely used by HMRC to argue disguised employment.
Mutuality of Obligation Exclusion
This clause explicitly states that the client has no obligation to offer work and the contractor has no obligation to accept it beyond the agreed project scope, directly rebutting the mutuality of obligation test established in case law including Carmichael v National Power plc. Clearly excluding ongoing obligations prevents HMRC from characterising the engagement as a rolling employment relationship, which is a critical consideration in long-running defence sector contracts.
Control and Working Practices
This clause defines the contractor's autonomy over how, when, and where the services are delivered, confirming that the client directs outcomes rather than dictating methods or working hours. Control is the central pillar of employment status case law stretching back to Ready Mixed Concrete v Minister of Pensions 1968, and HMRC's Check Employment Status for Tax tool places significant weight on demonstrable contractor autonomy when making IR35 determinations.
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Generate free →Frequently asked questions
Does a written contract alone guarantee outside-IR35 status for defence contractors?
No — HMRC assesses the actual working practices of an engagement, not just what the contract states, as confirmed by the Court of Appeal in Dragonfly Consulting Ltd v HMRC. A contract must accurately reflect the real day-to-day reality of the engagement to be effective as an IR35 defence. If the written terms contradict how the work is actually performed, HMRC will disregard the contract and apply employment status tests to the true arrangement.
Who is responsible for issuing a Status Determination Statement in a defence sector engagement?
Under the Chapter 10 ITEPA 2003 off-payroll working rules that came into force for the private sector in April 2021, the responsibility for issuing a Status Determination Statement (SDS) lies with the end client, provided they are a medium or large organisation as defined by the Companies Act 2006. The SDS must state whether the engagement falls inside or outside IR35 and provide reasoning, and the end client retains liability if they fail to take reasonable care in making that determination. Contractors should retain a copy of any SDS received as part of their IR35 compliance records.
Can security clearance requirements in a defence contract affect my IR35 status?
Security clearance obligations, such as Developed Vetting or Security Check clearances required under MOD contracts, do not in themselves push a contractor inside IR35, but HMRC may scrutinise them if they appear to restrict the right of substitution, since only the named individual may hold the relevant clearance. To mitigate this risk, the contract should acknowledge that any substitute would need to obtain equivalent clearance and that the obligation to provide a substitute remains with the PSC. HMRC's guidance confirms that a substitution clause remains valid even where the substitute must meet specific qualification or vetting requirements.
The information on this page is for general informational purposes only and does not constitute legal advice. Contracto generates AI-assisted contract templates — they are not a substitute for advice from a qualified solicitor. For high-value or complex engagements, always seek independent legal review.