IR35 Advice & Contract Review in Harrow
We review your contract and working practices and give you a written IR35 opinion you can act on.
- Full contract and working-practices review
- Written opinion with HMRC-ready rationale
- SDS challenge support
How do you work?
A badly-written contract can cost you a year's tax planning.
IR35 is the HMRC rule that decides whether you're really running your own business or whether, in reality, you're an employee of your client, wearing a limited company as a fig leaf. If HMRC decides you're the latter, the tax bill is catastrophic: employer's NI, employee's NI, PAYE on the full value of the contract, often going back years, plus penalties and interest.
Since the 2021 off-payroll reforms, medium and large private-sector clients are legally obliged to decide your IR35 status for you, via a Status Determination Statement (SDS). Many of them, nervous about getting it wrong, take the lazy route and blanket-ban outside-IR35 contracts altogether. Others issue an inside-IR35 SDS that looks wrong the moment you read it, because your actual working practices are clearly outside.
A written IR35 opinion from a qualified specialist, typically a 48-72 hour turnaround, detailed, properly reasoned, is the single most useful thing you can put in front of an end client to change an SDS. It's also the single most useful thing to have in your filing cabinet if HMRC ever asks. IR35 reviews are core work here, not an occasional sideline, and every review starts with a fixed written quote.
You'll recognise yourself in one of these.
The challenged contractor
Your end client has issued an inside-IR35 SDS and you think it's wrong. You need a written opinion with the reasoning spelled out, ready to put in front of their compliance team.
New contract review
You've been offered a new contract. The client says outside IR35, but the clauses worry you, substitution is weak, control is heavy, and there's a notice period that smells of mutuality.
Blanket-ban escape
Your client has decided all contractors go inside. You want ammunition to fight it, evidence that your role and working practices fundamentally don't match employment.
Ongoing monitoring
You've been outside IR35 for two years. You want a six-monthly status check to catch any working-practices drift before HMRC does.
From first call to everything handled.
- 1
60-second enquiry form
Tell us the situation, new contract review, challenging an SDS, ongoing monitoring, or a full enquiry defence. That's what we need to scope the review and quote it properly.
- 2
Fixed written quote in 48 hours
We come back within 48 hours with a fixed written quote for the review. IR35 is day-in, day-out work here, not something done once a quarter.
- 3
Initial call & scope
We'll talk you through the contract, the client, and how you actually work, and tell you on the call whether a full review is worth it, or whether the position is clearly one side or the other. No obligation; no fee for this part.
- 4
Written opinion if it's worth doing
If the position is genuinely contestable or the contract needs review, we'll confirm the fixed fee and typically deliver a 6-8 page written opinion within 48-72 hours, covering the three pillars, secondary indicators, relevant case law, a risk rating, and clause-by-clause renegotiation advice.
- 5
Challenge & follow-up
If you're challenging an SDS, we draft the formal disagreement letter citing specific grounds. Clients are legally required to respond within 45 days. The follow-up correspondence sits inside the engagement.
Fixed-fee reviews. The specialist quotes you upfront.
We quote a fixed written fee upfront after the initial call, never hourly, never creeping. For reference, standard UK IR35 contract reviews with a full written opinion typically range £250-£500. Full challenge packages that include the SDS disagreement letter and follow-up correspondence are usually quoted separately.
The economics are straightforward. A successful challenge that flips an inside-IR35 SDS back to outside commonly recovers the fee inside a single week of work under the corrected rate. A written opinion that sits in your filing cabinet unused still matters, it's evidence of due diligence that materially reduces HMRC penalties if an enquiry ever opens.
The initial call and the quote are free. You pay only the fixed fee agreed in writing before the review starts.
Tell us about your situation through the short form and we'll come back within 48 hours with a fixed written quote for this service.
Get a fixed quote for an IR35 reviewFree to use. No obligation.
Getting IR35 wrong is the most expensive mistake a contractor can make.
A contractor on £600 per day, outside IR35, through a limited company, takes home something in the region of £124,000 net from a full year's work. The same contractor, inside IR35 through an umbrella, takes home roughly £87,000 net. That's £37,000 a year , gone into employer's NI, apprenticeship levy, umbrella margin, and holiday-pay trickery.
Now consider HMRC opening a retrospective enquiry. If they rule you've been inside IR35 for the last three years of a £600-a-day contract, the bill, payable by you or your limited company, can reach £150,000 before interest and penalties. Contractor insurance helps, but only if your contract and working practices were actually defensible in the first place.
A properly-written IR35 opinion gives you three things: evidence that you did your due diligence (which reduces penalties dramatically if HMRC ever challenges); a roadmap of what to renegotiate before signing; and a client-facing document that often changes the SDS outright. The economics are absurd. Not getting a contract reviewed is the mistake.
The three pillars HMRC actually tests.
IR35 case law, from Ready Mixed Concrete (1968) through to Atholl House, Kickabout Productions and the PGMOL Supreme Court decision in 2024, boils down to three pillars. Get two clearly on your side and you're almost certainly outside. Get two against you and you're almost certainly inside.
Substitution
Can you send someone else to do the work in your place, at your expense, without the client's permission? A genuine, unfettered right of substitution is the strongest single indicator of self-employment. Most contracts contain a substitution clause, but many are worded so weakly, client approval required, skills must match exactly, substitute must pass client vetting, that the right is effectively meaningless.
Control
How much control does the client exercise over what, how, where and when you work? An employee is told. A self-employed contractor is engaged to deliver a result and largely left to their own methods. Red flags: set working hours, mandatory office attendance, line manager authority to reassign tasks, ID badges, performance reviews, being listed on the internal org chart.
Mutuality of obligation
Does the client have to offer you work, and do you have to accept it? An employee says yes to both. A contractor completes the specific engagement and walks. Red flags: rolling extensions without specified deliverables, language about "ongoing support", the expectation that you'll absorb new scope without renegotiation, notice periods that look like employment.
What changed in April 2021, and what the 2024 PGMOL decision means.
Before April 2021, IR35 in the private sector was your problem. You decided your status, you paid the tax if you got it wrong. After April 2021, if your end client is a medium or large business, the end client decides your status via an SDS and becomes liable for the tax if they get it wrong.
The effect has been predictable. Some clients, professional services, consultancies, banks, invested properly in case-by-case assessment. Others, nervous FTSE 250 in-house teams, particularly, blanket-banned outside IR35 altogether, forcing every contractor either inside or onto an umbrella. The blanket bans are almost always indefensible if challenged properly.
The 2024 PGMOL Supreme Court decision reshaped the test again. The court held that mutuality of obligation exists wherever there is paid work done in return for consideration, which is almost every contract. The weight has shifted decisively onto control and substitution. Many SDSs issued in 2022-2023, relying on MOO as the anchor reason, are now vulnerable to challenge. If your SDS was dated before May 2024, it's worth a fresh look.
IR35 for freelancers across Harrow & NW London
Areas we cover. Don't see your postcode? Get in touch, most of NW London is within range.
Core Harrow
- Harrow-on-the-Hill (HA1)
- Harrow Town Centre (HA1)
- Wealdstone (HA3)
- Pinner (HA5)
- Kenton (HA3)
- Stanmore (HA7)
- North Harrow (HA2)
NW London
- Edgware (HA8)
- Wembley (HA9)
- Kingsbury (NW9)
- Ruislip (HA4)
- Northwood (HA6)
- Greenford (UB6)
- Ealing Broadway (W5)
Everything else you want to know.
Can't see your question? Use the short form and ask, we'll answer it alongside your quote.
What's the difference between IR35 and off-payroll working?
IR35 is the underlying tax rule, in force since 2000. Off-payroll working rules are the 2017 (public sector) and 2021 (private sector) reforms that shifted the decision from the contractor to the end client. The tax treatment is the same, the question is who makes the call and who's on the hook for getting it wrong.
My client used CEST and it said inside IR35. Does that settle it?
No. CEST is HMRC's own tool, and HMRC will stand by a CEST result, but only if it was used honestly with accurate answers. Most inside-IR35 CEST results come from clients answering conservatively on substitution and control without checking with the contractor. A proper review identifies exactly where the CEST answers diverge from reality, which is the basis for the challenge.
How long does a contract review typically take?
Usually 48-72 hours from the point the specialist has the contract and your completed working-practices questionnaire. Expedited 24-hour turnaround is often available for an additional fee. We confirm the timing in your written quote.
Can a review be done before I sign?
That's the ideal time. A pre-signature review identifies clauses sitting on the wrong side of the line (weak substitution, heavy control, long notice periods) and produces specific rewording to send back to the client before signature. It's the cheapest form of IR35 insurance there is.
What if the client refuses to change the SDS?
The options are: (1) keep working under the inside-IR35 SDS, absorb the hit, and quietly look for a new contract; (2) escalate through the client's formal disagreement process (they must respond within 45 days); (3) if the case is strong, raise it with the client's senior tax function, they often overrule front-line compliance; (4) walk. We help you work out which path makes commercial sense.
Do I need an IR35 review if I work through an umbrella?
No. Umbrella workers are PAYE employees of the umbrella company, IR35 doesn't apply because the arrangement isn't self-employment. If you're on an umbrella and thinking of going back to a limited company, then yes, a review makes sense before you move.
What about HMRC investigations from years ago?
HMRC can normally go back four years for carelessness, six years for deliberate error, and up to twenty years in extreme cases. If you receive an opening letter, don't reply on your own, the first 30 days set the tone of the entire investigation. Use the short form and flag it as urgent; we'll prioritise the review.
Does IR35 apply if I'm a sole trader, not a limited company?
No. IR35 applies only to engagements through an intermediary, typically a personal service company (PSC) or, less commonly, a partnership. Sole traders invoicing clients directly are assessed under general employment-status rules, which are similar in principle but tested differently.
Is IR35 investigation insurance worth it?
Several providers offer cover including investigation defence, Qdos and Kingsbridge are the best-known. Policies only pay out if the contract and working practices were genuinely defensible, which is why having a written opinion on file matters even more. Many policies now require a contract review before cover attaches.
How often should status be rechecked?
Every six months on long-running contracts, and immediately if anything about the engagement changes materially, scope expansion, reporting line change, new client manager, extension beyond the original deliverable, or relocation. Six-monthly status monitoring is a common ongoing retainer, typically at a reduced fee for existing clients.
Is there a fee for the quote?
No. The initial call and the quote are free. We come back within 48 hours with a fixed written fee and you decide whether to proceed. No obligation, and nothing to pay unless you engage us.
What freelancers usually book alongside ir35.
Freelance Tax Returns
We prepare and file freelancer self-assessment returns, with every allowable expense checked.
Learn moreVAT for Freelancers
We handle VAT registration, scheme choice and quarterly returns for freelancers and contractors.
Learn moreSole Trader Accounts
We handle sole trader accounts end-to-end, from bookkeeping to the SA103.
Learn moreContractor Accountant (Ltd Co)
We run contractor limited companies day to day, payroll, dividends and corporation tax included.
Learn moreLet's take this off your plate.
A free 15-minute call. No obligation. We'll tell you what we'd do and what it costs.