What a good invoice description does
A line description has three jobs: tell the buyer what was delivered, let accounts payable match it to an approved purchase order or contract, and stand alone as a record months later when nobody remembers the project.
If a description fails any of those jobs, it costs you time. Either you answer questions, the invoice is returned, or it sits unpaid until someone notices.
Be specific without being long
Specific does not mean wordy. The pattern that works on most invoices is: deliverable + scope marker + period or phase. 'Brand identity design — logo and type system (Phase 1 of 2)' is specific in seven words. 'Consulting' is vague in one.
If the work was hourly, include the period and the number of hours. 'Marketing strategy support — March 2025 (12 hours)' is much more payable than 'Marketing — March'.
Match the buyer's language
If the buyer issued a purchase order with a specific name for the work, use that name on the invoice. If your statement of work calls a deliverable 'Phase 1 — Discovery', the invoice should say 'Phase 1 — Discovery'. The accounts team matches by exact wording first, then by amount, then by date.
Internal project codes you use in your own systems are not useful to the buyer. Translate them to the buyer's words on the invoice.
Worked example: a vague invoice rewritten
Before: one line, 'Consulting services, March 2025, £4,800.00'. The buyer's accounts team has no PO match, no deliverable list, and no idea whether this was strategy, support, or both. They send it back asking for a breakdown. Net effect: 11 days lost.
After: three lines. 'Marketing strategy workshop — 6 March 2025 (1 day on-site), £1,800.00'. 'Strategy support sessions — March 2025 (8 hours @ £225/hr), £1,800.00'. 'Q1 strategy memo — final draft, 28 March 2025, £1,200.00'. Same total. The buyer can match each line to the agreed scope and approve in a single pass.
The work did not change. The invoice did. Time-to-paid dropped from 25 days to 7.
Common mistakes
These are the description problems that slow payment most often:
- Vague single-word labels: 'Services', 'Consulting', 'Design', 'Project'.
- Internal project codes the buyer cannot decode (e.g. 'PRJ-0012-A').
- Bundling unrelated work into one line so the totals are unverifiable against the PO.
- Period missing on hourly or retainer work, so the buyer cannot place when the work happened.
- Using a long narrative paragraph instead of a short, structured line. Accounts payable scans, it does not read.
- Different wording on the invoice than on the contract, so the line cannot be matched on first pass.