IR35 calculator
A first read on whether a contract sits inside or outside IR35.
Contracting through your own company means the tax treatment changes with every engagement, and the rules that decide it are not in the contract you signed. Buzz handles the company, the filings and the day-to-day questions, and gives you a straight answer on where each contract sits.

Company accounts and a Corporation Tax return are the easy part of contracting. The part that moves real money is whether an engagement sits inside or outside IR35, who gets to decide that, and what you do when a client gets it wrong. If you work in IT or software, there is more detail on how we work with IT and software contractors.
For every public sector client, and for medium and large private sector clients, the client decides and issues a Status Determination Statement. Where the client is small, the decision stays with your own company. A private sector client is small unless it exceeds at least two of three limits: turnover above £10.2 million, a balance sheet total above £5.1 million, or more than 50 employees.
That single fact changes who carries the risk, so it is the first thing worth establishing on any new engagement. Clients must confirm their size in writing if you ask. Our plain-English guide to inside and outside IR35 works through the tests, and the IR35 calculator gives you a first read before you get a determination.
Responsibility for operating PAYE on umbrella company pay now sits with the recruitment agency that contracts with the end client, or with the end client where there is no agency. The umbrella remains your legal employer and your employment rights are unchanged.
What it changes is who HMRC pursues when the tax is not handed over, which is the mechanism behind most of the umbrella schemes that left contractors with bills they had not caused. It is worth knowing which company in your chain is actually operating your PAYE, and we will tell you what your payslip is showing you.
Status is decided contract by contract, not once for you as a person. You can hold three engagements at the same time and have them land differently, and a company carrying inside-IR35 work can still take outside work alongside it. Whether the company still earns its keep is a question worth asking once a year, not a decision to make in a hurry.
One monthly figure agreed in writing before you start, priced on how the company is set up rather than on your day rate. Questions mid-contract do not generate an invoice, which is the point — the decisions that cost money on contract work rarely wait for year end.
Most contractors stay too long with an accountant they have outgrown because moving looks like hassle in the middle of an engagement. It is not. We write for clearance and your records, register as your agent and set the software up while we wait. See how switching accountants works.
When a determination arrives, a client extends you past 24 months, or an agency changes how you are paid, you get a straight answer from someone who already knows your setup. No ticketing system, no three-day wait, no re-explaining the engagement every time.
You get a fixed monthly figure in writing after a 30-minute discovery call, priced on how the company is set up rather than on your day rate. A single-director company on one outside-IR35 contract is a different job from one running VAT, a second fee-earner and a director's loan. FreeAgent is included, worth up to £330 a year, and asking a question does not generate a bill — which matters on contract work, because the decisions that cost money happen mid-engagement rather than at year end.
It depends on the client. For every public sector client, and for medium and large private sector clients, the client decides and must give you a Status Determination Statement setting out the conclusion and its reasons. You can challenge it, and the client has to respond. Where the client is small, the decision stays with your own company under the older rules. A private sector client counts as small unless it exceeds at least two of three limits — turnover above £10.2 million, balance sheet total above £5.1 million, or more than 50 employees. If the client is anywhere near that line, ask them to confirm their size in writing; they are obliged to.
Income Tax and employee National Insurance come off the fee at source, broadly as though you were employed by the client, and there is no dividend route on that income. Your company carries on existing for everything else — it can still hold outside-IR35 work, other clients, and its own assets. Status is decided engagement by engagement, not once for you as a person, so you can genuinely hold three contracts at the same time and have them land differently. What inside IR35 is not is a reason to close the company on its own.
On an outside-IR35 engagement, yes, while the site is still a temporary workplace. It stops being one — and the journey becomes ordinary commuting you cannot claim — once you expect to spend 40% or more of your working time there over a period lasting more than 24 months. The test bites from the moment you expect to pass it, not when you actually do, so a 12-month contract extended to 30 changes the treatment from the date of the extension rather than at month 24. On an inside-IR35 engagement the rules treat it as a separate employment, so home-to-site travel is not deductible at all.
It follows the work rather than the other way round. If your contracts are genuinely outside IR35, your own company usually leaves you better off and gives you control over timing, pension contributions and how profit is drawn. If everything you can get is inside IR35, an umbrella removes the running costs and filings of a company you are no longer getting much from. Most contractors sit somewhere in between and the honest answer changes year to year, which is the argument for reviewing it annually rather than deciding once.
From 6 April 2026 the responsibility for operating PAYE on umbrella company pay moved to the recruitment agency that contracts with the end client, or to the end client itself where there is no agency in the chain. The umbrella is still your legal employer and your employment rights are unchanged — what changed is who HMRC pursues if the tax is not paid over, and agencies now carry that liability. In practice it should make the mini-umbrella and disguised-remuneration schemes that caught contractors out much harder to run.
Not necessarily, and that is worth a proper look rather than drift. A company with no outside work still costs you accounts, a Corporation Tax return, a confirmation statement and the admin around them, in exchange for benefits you are no longer getting. Closing it is not free either — there may be retained profit to extract, and how that is done makes a real difference to the tax. If you expect outside-IR35 work to come back within a year or two, keeping the company dormant is usually cheaper than closing and re-forming.
Yes, at any point in the year. You tell us to go ahead, we write to your current accountant for professional clearance and your records, register as your agent with HMRC and set up the software while we wait. Most handovers finish inside a couple of weeks and the delay is almost always the other firm's reply. Two things to check at your end: the notice period in your existing engagement letter, and whether work you have already paid for has actually been done. You do not have to make the awkward call — that part is ours.








