How to write an engineer invoice

What goes on an engineer invoice

Six things, in the order they belong on the page. The invoice generator opens an engineer / surveyor document with the lines already in place, so most of this is checking rather than typing.

1. Name the deliverable, with its reference. Report number, drawing number, revision. It is what the client files it against.
2. Separate the site visit from the desk work. Attendance and reporting are different work and often different rates.
3. State whether the fee is fixed or hourly. And if hourly, show the hours against each activity.
4. Charge revisions beyond the agreed number. Design revisions are open-ended unless the scope closes them.
5. Itemize expenses and third-party costs at cost. Travel, testing, searches and specialist input are not your fee.
6. Use the client purchase order reference. Commercial and contractor invoices without one do not get approved.

The lines an engineer invoice usually carries

The generator opens with these lines when you pick Engineer / surveyor. The figures are placeholders to type over, not a going rate.

Add, rename, reorder or delete any line, and set tax per line where it applies. Priced as they open, that comes to $2,600 before tax.

How to write an engineering invoice, step by step

1. Quote the purchase order and project. Open the engineer / surveyor invoice and enter the PO and the project name. On contractor work, the PO is the difference between being paid this month and next.
2. Name each deliverable with its reference. Calculations package C-01, drawings S-01 to S-04. The client already has these on their desk, so the invoice should point to them.
3. Separate the site visit. The survey and measurement is time out of the office, so it has its own line and date.
4. Count the revisions. Say how many revisions were included and how many were issued. A revision beyond the agreed number is a new line, not a favor.
5. Add certification, then send. Sign-off is its own line once the checks are done. Set 30 days and send it with the deliverables listed.

Engineering invoice example, filled in

A structural job for a builder: a site survey, the beam calculations, drawings and the certificate. The PO and the drawing references are at the top, because the person approving it will check them against what is already on their desk.

Subtotal $2,600, tax $260, total $2,860. Each deliverable has its own line and reference, so a contractor's accounts team can match the invoice to the documents without calling you. The revision note sets out what the next change will cost before it is asked for.

Fixed fee against hourly, and pricing work you cannot scope in advance

A structural calculation for a defined opening is a fixed fee. An investigation into why a building is moving is not, and pricing the second like the first is how engineering work loses money.

Use fixed fees where the deliverable is defined and hourly where the extent of investigation is genuinely unknown, and say which applies on the fee proposal and again on the invoice. On hourly work show the hours against activity: site attendance, analysis, drafting, reporting. It converts an abstract figure into a record of work.

Where a fixed fee job turns out to need investigation nobody anticipated, raise it as a variation before doing the work. It is far easier to agree an additional survey in advance than to explain an unexpected figure against a fixed fee afterwards.

Revisions, and the drawing that changes six times

Every engineering practice has a project where the architect changed the layout repeatedly and every change meant recalculating.

The commercial answer is in the scope: state the number of revisions included, and invoice further revisions as their own line with the revision number and the instruction that caused it. Revision C following architect layout change of a stated date is checkable. Additional design work is not.

This matters more in engineering than almost anywhere else, because the work is invisible. A recalculated frame looks identical to the client and takes as long as the first one.

Contractors, main accounts and getting paid in a construction chain

Invoicing a main contractor is a different exercise from invoicing a homeowner, and the reason invoices sit unpaid is almost never the quality of the engineering.

You need the purchase order number, the correct site and project reference, the application or valuation period where the contract works that way, and descriptions matching those in your fee proposal. Contractors reconcile against orders, not against descriptions.

Also check the payment terms in the appointment before you invoice, because construction payment cycles are set by contract and by statute in many places. Invoicing a day after a valuation date can cost you a month, and that is a mistake made in the office rather than on site.

Hourly, fixed price or per unit: how engineers price the work

Engineering and surveying work is a fixed fee where the deliverable is defined and hourly where the extent of investigation genuinely is not. Pricing an investigation like a calculation is the standard way this work loses money.

Charge revisions beyond the agreed number. A recalculated frame looks identical to the client and takes as long as the first one, which makes engineering the discipline where unbilled rework is least visible and most expensive.

Working out what to charge

Engineering fees depend on the risk, the scope and the jurisdiction, so a figure from a web page is no use. The billable hours calculator shows how many hours a fixed fee has to cover, and the service price calculator turns those hours into a fee.

Getting paid once it is sent

Contractors pay on a monthly cycle, so get the invoice in before their cut-off date with the PO on it; on new clients and larger commissions, take a first payment on appointment. If the due date passes, the late fee calculator works out what your terms allow and the due date calculator sets the new date.

Five dates decide whether an engineer gets paid on time, and four of them are set before the work starts.

Mistakes that cost engineers money

• Deliverable not referenced. The client cannot match the invoice to the report they hold.
• Site visits inside a single fee. Attendance and analysis are different work at different rates.
• Unlimited revisions implied. A recalculation the client cannot see, done for free, repeatedly.
• Third-party testing marked up quietly. A small gain against a large loss of trust.
• No purchase order on contractor work. Correct, complete and never approved.

Engineer / surveyor invoice questions

Free engineer invoice template

The free engineer invoice template opens with the lines above already priced, in any of 52 designs made for the trade, and exports a print-ready PDF with nothing saved to a server. Opening a design needs a free account.

Invoicing guides for related trades

Everything on this site, set up for engineers

The whole toolkit, with the reason each one matters to engineers rather than in general. The four marked links open with engineer / surveyor already selected.