SimpleReturns

Company tax returns for locum doctors and dentists

Reviewed by Lee Jones, Founder · Updated 17 July 2026
The short answer

If you work locum shifts or private sessions through your own limited company, the filing job is the same as for every company: a Company Tax Return to HMRC and a set of accounts to Companies House, even in a loss year. Your version has three special features: your income is shift and session fees paid to the company, your costs are things like registration, indemnity and travel between sites, and hanging over it all is IR35. This guide is honest about which parts are simple and which part genuinely needs an accountant.

Official source. This guide is a plain-English summary of official GOV.UK guidance, not advice. The authoritative source is Company Tax Returns on gov.uk. Always rely on that over our summary.

What counts as your company's income?

Everything the company was paid for your work. For most locums that is some mix of three streams: locum shifts billed through an agency, private practice sessions, and NHS session work where the trust or health board pays your company. All of it is the company's income and belongs on the return, even in a quiet year.

Your tax bill is then worked out on the profit, which HMRC calculates its own way rather than just copying the accounts figure. Small companies pay 19% on profits up to £50,000, and bigger profits move towards 25%.

The big one: what does IR35 mean for your return?

IR35, properly called the off-payroll working rules, is the reason locum tax gets complicated. The honest, short version: for many NHS engagements it is the hospital or health board, not you, that decides whether the rules apply, because public bodies and larger organisations make that call for people who work through their own companies. When they decide the rules do apply, tax and National Insurance come off before the money ever reaches your company.

Income already taxed this way is treated differently on the company's return from your ordinary outside-IR35 work. We are not going to explain those mechanics here: this is genuinely a job for an accountant, and we would rather say so plainly than pretend it is simple.

The trap is mixing. Plenty of locums have a year where some engagements were inside the rules and some outside, all flowing into one company bank account. That mixed year is exactly where a casual return goes wrong, so get an accountant across the inside-IR35 part before anything is filed.

What can your company claim?

The rule behind every cost is simple: it has to be for the business. For a locum doctor or dentist the usual list looks like this:

  • Registration and indemnity. Fees you must pay to be able to do the job at all, like professional registration and indemnity cover, are the kind of cost the tax system accepts when the company pays them for its work. HMRC keeps an official list of approved professional bodies; fees needed for the work and paid to a body on that list sit on solid ground.
  • Royal college and society memberships. Annual memberships that are relevant to the work follow the same logic: check the body is on HMRC's approved list.
  • Training and courses. This area has a real line in it: training that keeps your existing skills up to date is on much safer ground than training that teaches you a brand-new skill, so ask an accountant before assuming a big course is claimable.
  • Equipment and workwear. Loupes, instruments, a decent examination kit: equipment the company buys for the work can be claimed in full against profit in the year of purchase, up to a very high yearly limit. Specialist workwear like scrubs and theatre footwear is kit for the job too; ordinary clothes you could wear anywhere are not a business cost.
  • Travel between sites. When you drive your own car to shifts, the company can pay you a set tax-free amount per business mile, currently 55p for the first 10,000 miles in a year and 25p after that. But whether a journey counts as a business journey depends on whether each site is a permanent or a temporary workplace, and for a locum moving between hospitals that area is genuinely fiddly. Have an accountant set your travel rules up once, then follow them.

One thing we will not advise on: whether to stay in the NHS pension, pay into a pension through the company, or do both is a personal financial decision, so take proper advice before choosing. Our guide on pension contributions through a limited company explains the basics without telling you what to pick.

What does filing look like with us?

At year end your company has two deadlines to keep apart. Your accounts go to Companies House within 9 months of your year end, and the Corporation Tax itself is due at about the same time, 9 months and 1 day after the year end. Your Company Tax Return, the CT600, then goes to HMRC within 12 months of the year end. A late return costs £200 from the very first day. HMRC's own free filing service has closed, so every company now files through commercial software.

SimpleReturns is built for the straightforward version of your company: engagements outside the off-payroll rules, invoicing for shifts and sessions, both filings done without learning accounting. You upload the company bank statement and answer a few plain-English questions, no jargon. You review every figure on one screen before anything is sent, then we file both returns: the tax return to HMRC and the accounts to Companies House. Free to start, no card needed, £99 flat for both. If your year mixes inside-IR35 income with outside work, we will say so plainly and point you at an accountant for that part, because honest is cheaper than wrong.

Common questions

The hospital already takes tax off before paying my company. Do I still have to file?

Yes. If HMRC has sent your company a notice to deliver a return, it has to go in, even in a loss year. Income that arrived after off-payroll tax was taken off is treated differently on the return, and that part is worth an accountant's eyes before anything is filed.

Can the company pay my professional registration and indemnity?

Fees you must pay to be able to do the job are the kind of cost the tax system is designed to accept, and HMRC publishes an official list of approved professional bodies. If a fee is needed for the work and the body is on that list, it belongs on the company's books; if you are unsure about one membership, check the list or ask us.

Are my scrubs claimable?

Specialist workwear the company buys for the job, like scrubs and theatre footwear, sits with your other kit. Ordinary clothes you could wear outside work are not a business cost, however often you wear them to the surgery.

Is SimpleReturns right for me if some of my work is inside IR35?

We are honest about this one. If all the company's income is straightforward outside-IR35 work, we are built for you: bank statement in, plain-English questions, both filings for £99. If your year mixes inside and outside work, the inside part needs an accountant, and we will tell you so rather than file something casual over the top of it.

Want your locum company's return filed for you?

You upload the company bank statement and answer a few plain-English questions, no accounting words. We sort the shift and session income and the registration, indemnity and travel costs, work out the profit and the Corporation Tax, and build both filings: the tax return for HMRC and the accounts for Companies House. You review every figure before anything is sent. Free to start, no card needed, and £99 flat covers both.

Start your return

And if your year mixes inside-IR35 income with outside work, we will say so plainly and point you at an accountant for that part, because honest is cheaper than wrong.

General guidance, not advice. This guide explains how the rules generally work for small UK limited companies. It isn't tax advice for your specific situation, if you're unsure, check with us or an accountant.