An IR35 Status Determination Statement (SDS) is the end client's written conclusion on whether an engagement sits inside or outside the off-payroll working rules. When that determination is reversed part-way through an engagement, the tax and contractual picture shifts sharply. The professional indemnity (PI) picture moves more slowly and more predictably. This entry sets out what a reversal does to PI cover, and where the real exposures sit.
Under Chapter 10 of the Income Tax (Earnings and Pensions) Act 2003, in particular section 61T, medium and large end clients must issue an SDS for every contractor engagement caught by the off-payroll rules. HMRC's Employment Status Manual at ESM10011 to ESM10025 sets out the client-led determination process, and the CEST tool is HMRC's preferred first-pass assessment. The SDS must be given to the contractor and to the party immediately below the client in the supply chain, with reasons. The contractor has a statutory right of disagreement under s.61T(6); the client then has 45 days to confirm or issue a new determination.
The PI policy attaches to the professional activity, not to the tax status of the person carrying it out. A contractor delivering IT services on Monday is delivering the same IT services on Tuesday if the SDS flips overnight. The wording responds to negligent acts, errors or omissions in professional services — it does not usually mention IR35 at all.
If the contractor holds PI in the name of their own limited company, the cover typically continues on a claims-made basis regardless of the SDS position. New work billed through the same limited company continues to be insured under the same policy, subject to the usual disclosure obligations at renewal.
Where the engagement moves onto an umbrella after an inside-IR35 determination, PI is often provided through the umbrella's own arrangements. These vary widely. Some umbrella schemes carry group PI that names the contractor by extension; some carry no PI at all and expect the contractor to hold their own. The wording, limit, excess and geographical scope all need to be checked before the first inside-IR35 timesheet is submitted.
This is the point most often missed. A reversal changes the tax treatment of future work; it does not retrospectively unwind the professional work already done. Errors made during the outside-IR35 period can be discovered months or years later, and the contractor's limited company remains the legal author of that work. Legacy PI cover, on a claims-made basis, needs to keep responding to those historical liabilities — either through continued renewals or through run-off cover if the limited company later winds down.
Many contractor agreements include an indemnity from the contractor to the end client for tax, national insurance and interest the client is later required to pay to HMRC on a reversed determination. This is a tax and contractual exposure, not a professional indemnity claim, and a PI policy will not respond to it. Cover for that risk sits under IR35 tax investigation or tax liability insurance, a separate product.
Worked example — illustrative only. An IT contractor operates outside IR35 from April 2024 to January 2026, invoicing through their limited company and holding £1m of PI in the company name. In February 2026 the end client re-issues the SDS as inside IR35. The limited company continues, but new billable work now flows through an umbrella. Two PI questions arise. First, the limited-company PI continues to respond to any claim arising from the April 2024 to January 2026 work — the reversal does not extinguish those historical liabilities and cover remains in force as long as the policy is renewed. Second, the new work under the umbrella needs the umbrella's PI arrangements checked: limit, wording, whether IT services are within scope, and whether the contractor is named or covered by extension.
The wider IR35 and PI picture sits in the IR35 contractor PI insurance entry, and the sector view is in the IT professionals PI insurance UK guide 2026.
Apex Insurance Brokers Limited is authorised and regulated by the Financial Conduct Authority. Firm reference number 724952. This entry is general information, not advice on any particular policy.