Your first invoice as a locum: six things practices check

A late invoice almost always comes down to one of six missing pieces. Get them right on the first invoice and the practice pays you on their normal cycle. Miss them and you sit in an exceptions queue for a fortnight.

1. A unique invoice number

Every invoice needs a unique, sequential reference. The practice uses it to find your record when they pay you. "Invoice 1" is fine; so is SES-2026-001. What matters is that you never issue the same number twice. HMRC requires this, and most accounting software refuses duplicate entries.

2. Your legal name and address

Not your business trading name, your actual legal name as the self-employed individual. Practices issuing 1099-style or end-of-year summaries need to match what HMRC sees. If you trade as "North London Medical Locums" but are Dr Sarah Jones on your tax return, use "Dr Sarah Jones trading as North London Medical Locums" at the top.

3. The practice's correct billing details

Ask for their accounts email (not the practice manager's personal inbox) and invoice format preference on day one. NHS primary care practices increasingly use purchase-order systems, especially those in PCN federations. Get a PO number if they require one, invoices without a PO number bounce back.

4. Work dates, not just sessions

"Session at Hillside Practice, March 2026" is not specific enough. Write: "Afternoon surgery at Hillside Practice, 18 March 2026 (1pm–5pm)". The date is what lets the practice match your invoice to a rota and a session log.

5. The agreed rate and total

If you agreed £95 for a session by email, put "£95 per session (agreed by email 2 March 2026)". This catches disputes before they become arguments. For hourly work, show: rate, hours, product.

6. Payment details exactly as your bank expects

Sort code, account number, account name. Not "my usual account" or a scan of a bank card. Mistyping a sort code sends money to someone else's account and it is genuinely difficult to recover.

What is not required

You do not need a VAT number unless you are VAT-registered (most locums under £85,000 turnover are not). You do not need your National Insurance number on invoices, keep that for HMRC only. You do not need a logo, a quote number, or terms and conditions on the face of the invoice. Keep it simple.

Payment terms

UK standard is 30 days from invoice date. Some NHS organisations pay faster under Prompt Payment Code, many are slower. Two patterns help:

• State the due date on the invoice, not just "net 30". People read the date.
• Send on the day you do the session, not at month-end. A same-day invoice is processed while the session is fresh in the practice manager's mind.

What to do when an invoice goes unpaid

Chase once at 21 days, politely, attaching the PDF so no one has to search their inbox. Chase again at day 35 with a clearer note. For anything past 60 days, name a person at the practice and ask who owns the exception, nearly every overdue invoice is lost in a process, not refused on principle.

Sessional generates practice-ready invoice PDFs with every required field from your session log, and the chase button handles the follow-ups at the right cadence so you are not the one writing awkward emails.