Private Investigator Invoice Template
A private investigator invoice should show dates, hours by activity type, expenses itemized at cost, the case or matter reference, and the retainer balance before and after. It should never contain findings, subject details, or investigative substance — the invoice is a financial record that travels. ShowTheReceipts saves those lines and keeps the retainer balance on every invoice automatically.
Header block
- Business name, PI license number, phone
- Client — law firm, attorney, or individual
- Case / matter reference
- Billing period
- Invoice number and terms
Time lines
- Investigative hours — date, hours, general activity
- Surveillance hours — with stated minimum per deployment
- Travel time — per your engagement terms
- Report preparation
- Testimony / deposition — higher rate, half-day minimum
Expenses — at cost, itemized
| Expense | Basis |
|---|---|
| Mileage | Per mile |
| Database / records searches | At cost |
| Court filings and copies | At cost |
| Tolls, parking, lodging | At cost, receipted |
Don’t mark up an expense — it’s checkable, and credibility with a firm is worth more than the margin you’d squeeze out of it.
Retainer block
- Opening retainer balance
- Charges this period
- Closing balance
- Replenishment threshold and amount
What not to do
- Don’t put findings, names, or investigative substance on the invoice
- Don’t bill vague blocks with no dates
- Don’t mark up pass-through expenses
- Don’t wait until the retainer is exhausted to ask for a top-up
Frequently asked questions
How much detail should activity descriptions carry?
Enough to justify the time and nothing more — 'field surveillance, 6 hours' rather than a narrative. Billing detail and investigative detail are different documents with different audiences.
Should travel time be billed at full rate?
Decide it in the engagement letter — full rate, reduced rate, or included beyond a radius — and then bill it consistently. Any of the three is defensible; what isn't is a client discovering the rule from an invoice.
How should the retainer be shown?
Opening balance, charges this period, closing balance, and the replenishment threshold. It's three lines and it eliminates the single most common billing conversation in the profession.
Can this invoice go to a law firm's client?
Assume it will. Firms pass investigative costs through to their clients, which is exactly why the document should contain hours, expenses, and nothing that would be uncomfortable read by anyone in the matter.