Filing self assessment as a locum doctor requires careful attention to detail and understanding of specific medical professional requirements. This locum doctor self assessment filing guide walks you through the complete process, from initial preparation to final submission.

Most locum doctors must file self assessment returns due to their self-employed status, mixed income sources, and complex tax situations involving IR35, professional expenses, and multiple income streams.

Who Must File Self Assessment as a Locum Doctor

You must file a self assessment return if you work as a locum doctor and have:

  • Self-employed locum income over £1,000 per year
  • Mixed employment and self-employed income
  • Income from multiple sources (NHS, private practice, agencies)
  • Professional expenses to claim
  • Untaxed income over £2,500

This applies to locum GPs, locum consultants, and doctors working through agencies or directly with practices. Even if you work some shifts through PAYE, additional self-employed income typically requires a return.

Key Deadlines for Locum Doctor Returns

Missing deadlines triggers automatic penalties, regardless of whether you owe tax:

  • 31 October 2025: Paper return deadline for 2024/25 tax year
  • 31 January 2026: Online return deadline and tax payment due
  • 31 July 2026: Second payment on account due (if applicable)

Late filing penalties start at £100 and escalate quickly. A return filed one day late incurs the same penalty as one filed three months late, so timing is crucial.

Documents You Need Before Starting

Gather these documents before beginning your locum doctor self assessment filing guide process:

Income Records

  • All P60s and P45s from employed positions
  • Invoices sent to practices, hospitals, and agencies
  • Payment records from all income sources
  • Bank statements showing locum payments
  • Agency statements and contracts

Expense Documentation

  • GMC registration and revalidation fees
  • Professional indemnity insurance (MDU/MPS)
  • BMA membership and subscriptions
  • CPD courses and training costs
  • Travel expenses between locations
  • Professional clothing and equipment

Step-by-Step Filing Process

Step 1: Register for Self Assessment

If this is your first return, register online at gov.uk. HMRC will send your Unique Taxpayer Reference (UTR) by post, which takes 5-10 working days. You cannot file without this reference.

Step 2: Choose Your Filing Method

Most locum doctors should file online using HMRC's system or commercial software. Online filing offers longer deadlines, immediate confirmation, and automatic calculations. Paper returns have earlier deadlines and higher error rates.

Step 3: Complete Employment Section

Enter all PAYE employment income from P60s and P45s. This includes any salaried positions, employed locum work, or other medical roles where tax was deducted at source.

Step 4: Self-Employment Section

This is typically the largest section for locum doctors. You'll need:

  • Total turnover (all locum income received)
  • Allowable business expenses
  • Accounting method (cash or accruals basis)
  • Business description ("Medical locum services")

Most locum doctors use cash basis accounting, which means income and expenses are recorded when money changes hands, not when invoices are raised.

Step 5: Claim Professional Expenses

Locum doctors can claim legitimate business expenses against their self-employed income:

  • Professional fees: GMC, royal college, indemnity insurance
  • Travel: Between different work locations (not home to regular workplace)
  • Training: CPD, courses, conferences directly related to work
  • Equipment: Stethoscopes, medical bags, professional clothing
  • Communication: Proportion of phone bills for work calls

Keep detailed records and receipts. HMRC may request evidence during investigations.

Step 6: Other Income and Reliefs

Include any other income sources such as rental income, savings interest, or private practice earnings. Also claim eligible reliefs like pension contributions or charitable donations.

Step 7: Review and Submit

Check all figures carefully before submission. The system will calculate your tax liability automatically. Pay any tax due by the 31 January deadline to avoid interest charges.

Common Mistakes to Avoid

Following this locum doctor self assessment filing guide helps avoid these frequent errors:

  • Mixing business and personal expenses: Only claim expenses wholly for business use
  • Poor record keeping: Maintain detailed records for at least 5 years
  • Incorrect IR35 treatment: Understand whether you're inside or outside IR35 for different contracts
  • Missing income sources: Include all payments, even small amounts
  • Incorrect accounting basis: Most locums should use cash basis, not accruals

IR35 Considerations for Locum Doctors

IR35 rules determine whether your locum work is treated as employment or genuine self-employment for tax purposes. This affects both your tax liability and how you complete your return.

If caught by IR35, you cannot claim business expenses and must treat the income as employment income, even though you're technically self-employed. The end client (practice or trust) should make this determination, but you remain responsible for correct reporting.

Payment on Account Requirements

If your previous year's tax bill exceeded £1,000, you must make payments on account. These are advance payments toward next year's tax bill, due on 31 January and 31 July.

For example, if your 2024/25 tax bill is £8,000, you'll pay £4,000 on 31 January 2026 (balancing payment) plus £4,000 on account for 2025/26. Another £4,000 payment follows on 31 July 2026.

Record Keeping Requirements

HMRC requires locum doctors to keep records for at least 5 years after the 31 January submission deadline. This includes:

  • All income records and bank statements
  • Receipts for claimed expenses
  • Contracts and working arrangements
  • Mileage logs for travel claims
  • Professional registration documentation

Digital records are acceptable, but ensure they're backed up securely. Poor record keeping is a common trigger for HMRC investigations.

When to Seek Professional Help

Consider professional assistance if you have:

  • Multiple income sources and complex arrangements
  • Significant business expenses or capital purchases
  • IR35 uncertainty across different contracts
  • Previous HMRC enquiries or compliance issues
  • Plans to incorporate your practice

A specialist medical accountant understands the unique challenges facing locum doctors and can ensure compliance while maximizing legitimate tax savings. Our specialist services are designed specifically for medical professionals navigating complex tax situations.

After Filing Your Return

Once submitted, HMRC will send a calculation showing any tax due. Pay this by 31 January to avoid interest and penalties. Keep a copy of your return and payment confirmation.

HMRC may open an enquiry into your return within 12 months of submission. This doesn't necessarily indicate problems, but good record keeping makes the process straightforward if selected.

Start preparing for next year's return immediately by setting up proper record-keeping systems and saving appropriate amounts for your tax liability.