1. What every civil / mechanical / electrical engineer (pe) invoice must include

A compliant civil / mechanical / electrical engineer (pe) invoice has eight parts: your business name and contact info, a unique invoice number, issue date, payment due date, the customer's name and address, an itemized list of work, the total amount due, and accepted payment methods. If you're collecting sales tax, that line is required too.

2. Set your line items

Most civil / mechanical / electrical engineer (pe)s structure invoices around these 4 categories:

Project fee — billed by flat.
Hourly engineering — billed by hour at a ~$175 default.
PE stamp & sealing — billed by flat.
Site visit — billed by flat.

3. Set payment terms

The standard for civil / mechanical / electrical engineer (pe)s is Net 30 — payment due within 30 days of the invoice date. Most civil / mechanical / electrical engineer (pe)s also require a 25% deposit upfront before starting work. Spell out late-fee terms (most states cap monthly late fees around 1.5%) and accepted payment methods on the invoice itself.

4. Licensing & legal disclosures

PE license required to stamp drawings or sign engineering opinions. Discipline-specific rules apply.

5. Send and follow up

Send the invoice the same day work is completed (or upon milestone for larger projects). Use software that tracks opens and lets the customer pay by card or bank transfer in one click — the average civil / mechanical / electrical engineer (pe)-class invoice gets paid 2× faster when the customer can pay online without leaving their inbox.

Average invoice

$6,500

Standard terms

Net 30

Typical deposit

25%

BLS code

17-2051

State-by-state civil / mechanical / electrical engineer (pe) invoicing guides

State rules differ on sales tax, statutory late fees, and contractor disclosure requirements. Pick your state for a guide tuned to local law.

How to Invoice as a Civil / Mechanical / Electrical Engineer (PE): Step-by-Step Guide