Since the off-payroll reforms, the person who needs advice is usually not the one who makes the decision. For a medium or large client the CLIENT determines your status and issues a Status Determination Statement, and the fee-payer, normally the agency, carries the tax if the determination is wrong. So advice bought by a contractor is no longer insurance: it is evidence, and an argument to put to whoever made the call. That changes what is worth paying for and what is not.
Who decides, and who pays if the decision is wrong
For engagements with medium and large clients, the client decides and must give a Status Determination Statement with its reasons to the worker and to the party it contracts with, taking reasonable care. The fee-payer deducts and pays over the tax. If HMRC later disagrees, the liability sits in the chain rather than with you, unless you are the one who made the determination, which happens where the client is small: then the original rules apply and your own company is responsible. Knowing which of those two situations you are in is the first piece of advice, and it is free.
What an IR35 review of the contract actually buys
A reviewer reads the written contract and, if the work is done properly, asks about the working practices as well, because the practices win where the two differ. The output is an opinion: a view on control, substitution and mutuality of obligation, with the clauses that help and the clauses that do not. Its value is evidentiary. A determination challenged with a documented review, taken before the engagement started, is a much better position than one challenged with a recollection. Its value is NOT protective on its own: an opinion does not bind HMRC and does not move liability.
IR35 accountants, an IR35 specialist, and what to ask them
A contractor accountant does your company's compliance and will usually have a view on status; a status specialist does reviews and disagreements and nothing else. Both are worth having for different reasons, and neither is regulated for this specifically, so the questions that separate them are practical. Will you review the working practices or only the contract? Will you put the opinion in writing with reasons? Will you support a challenge to a client's determination, and at what cost? What happens if HMRC opens an enquiry two years from now, and is that covered or extra?
The client-led disagreement process
If you think a determination is wrong there is a statutory route: you make representations to the client, and the client must respond within 45 days with either a new determination or the reasons for keeping the old one. That process is free, it is the only one with a deadline attached, and it is where a written review earns its fee. Most contractors never use it, which is why blanket determinations persist: an unchallenged blanket assessment costs a client nothing.
IR35 compliance, once the decision is made
Inside IR35 there is very little left to comply with on your side: the fee-payer deducts PAYE before the money reaches you, and your own company has almost nothing to do. Outside, compliance means keeping the evidence that supported the determination: the contract, the SDS, the review, and a record of how the work was actually done, because a challenge years later will turn on the practices rather than on the paperwork. Advice that produces a filing cabinet is worth more than advice that produces a conclusion.
Questions people ask about ir35 advice
Do I need an IR35 accountant?
You need someone who will look at working practices as well as the contract and put an opinion in writing. Whether that is your accountant or a status specialist matters less than whether the opinion is documented and dated before the engagement.
How much does an IR35 contract review cost?
Prices are not published consistently and are quoted per engagement, so ask for a fixed fee in writing along with what it covers: contract only, or contract and working practices, and whether support for a disagreement is included.
Can I challenge a client's IR35 determination?
Yes. You make representations to the client and it must respond within 45 days with a new determination or reasons for keeping the old one. It is free and it is the only route with a statutory deadline.
Does a positive review protect me from HMRC?
No. It is evidence, not insurance. It does not bind HMRC and it does not move liability, which since the reforms usually sits with the client or the fee-payer rather than with you.