The Bottom Line
- If it is your first time, you typically need to register for Self Assessment by 5 October following the end of the tax year.
- Online returns and payment are commonly due by 31 January; if you have payments on account, the second payment is often due 31 July.
- Treat SA like a micro-process: 10 minutes/week beats a 10-hour January scramble.
- Your ‘evidence’ stack: P60/P45/P11D (if relevant), invoices, mileage log, bank statements, and receipts for allowable costs.
- Never file based on vibes. Reconcile income + expenses first, then submit.
The deadlines clinicians actually miss (and how to stop doing that)
These dates are non-negotiable calendar anchors for most people filing SA:
• Register (first time): typically by 5 October after the end of the tax year.
• Paper return: typically by 31 October.
• Online return + tax payment: typically by 31 January.
• Second payment on account (if applicable): typically by 31 July.
Your solution is not motivation. It is a system: a monthly ‘reconciliation day’ and a tax reserve account.
Who needs Self Assessment in the real world (doctor edition)
Common triggers for clinicians include: locum income paid gross (self-employed/sole trader), income streams outside PAYE, certain types of untaxed income, and situations where HMRC requires a return.
If you are PAYE-only, you may not need SA, but do not assume. The correct move is: check your HMRC account, check any HMRC letters, and speak to an accountant if your income profile is multi-stream.
First-time setup (30 minutes, once)
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1) Create/access your HMRC online account
Make sure you can sign in reliably. Store recovery codes safely. If you cannot log in smoothly, everything downstream breaks.
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2) Register for Self Assessment (if required)
If this is your first time and you need SA, register early. The friction is not the form; it is waiting for post/credentials while January approaches.
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3) Build a single ‘SA folder’ (physical or digital)
Create subfolders: Income, Expenses, Mileage/Travel, Pension/Benefits, HMRC Letters, Prior Returns. This reduces decision fatigue.
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4) Create a weekly capture habit (10 minutes)
Every week: file receipts, update mileage, and note any unusual payments. You are preventing ‘memory-based accounting’.
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5) Set a monthly reconciliation day
Once a month: total locum income, match to bank entries, and sanity-check expenses. This becomes your ‘pre-filing’ work.
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6) Ring-fence tax (do not trust yourself)
Move a fixed % of gross locum income into a separate ‘Tax Reserve’ account immediately on payment. Adjust later, but always reserve early.
The most common clinician error
Treating Self Assessment as a January admin task.
It is not. It is a year-round recordkeeping workflow. The filing is the final click — the work is done in the 12 months before.
PAYE + locum income: how to avoid the classic confusion
If you have multiple income streams (e.g., a salaried post plus locum sessions), your filing workload is not ‘double’ — but your error risk is.
Practical rule: keep a separate bank account for locum income/expenses where possible, so your bookkeeping is not mixed with life spending.
5-minute pre-submit checklist
Before you submit:
1) Income totals match bank totals (no missing invoices).
2) Expenses are defensible in one sentence each.
3) Mileage/travel has dates + purpose.
4) You understand whether payments on account apply.
5) You have saved a PDF copy of the submission and your working notes.
SourceGOV.UK — Self Assessment: deadlines (official)
Open Link SourceGOV.UK — Register for Self Assessment (official)
Open Link SourceGOV.UK — Payments on account explained (official)
Open Link