Contractor Invoicing Guide: How to Bill for Construction & Trade Work

Contractor invoicing follows different rules than typical service or freelance billing. Whether you're a general contractor managing a $500,000 build, an electrician billing for a commercial fit-out, or a plumber invoicing a residential repair, your invoices need to handle progress billing, retention holdbacks, change orders, and materials markups — things most invoicing guides ignore entirely. The Small Business Administration emphasizes that cash flow management is critical for construction businesses, where payment cycles routinely stretch 60-90 days.

This guide covers everything contractors and tradespeople need to know about invoicing, from residential service calls to large commercial projects.

How Contractor Invoicing Differs from Standard Invoicing

Contractor invoicing has unique requirements that set it apart:

Understanding these differences is essential for getting paid reliably in the construction industry.

Types of Contractor Invoicing

Progress Billing (Application for Payment)

The most common method for projects over $10,000. You bill periodically (usually monthly) based on the percentage of work completed. Each invoice — often called an "application for payment" — shows:

• Original contract amount
• Work completed to date (by line item)
• Materials stored on site (not yet installed)
• Retention withheld
• Previous payments received
• Current amount due

Example progress billing breakdown:

AIA-Style Invoicing

The American Institute of Architects (AIA) G702/G703 forms are the standard for commercial construction billing. These standardized forms include a schedule of values, percentage of completion, and retention calculations. Many general contractors and project owners require AIA-format invoices.

Even if you don't use official AIA forms, modeling your invoices on this structure adds professionalism and meets client expectations on larger jobs.

Time and Materials (T&M)

Bill for actual labor hours at agreed rates plus materials at cost plus markup. T&M works when the scope is undefined or constantly evolving:

• Labor: Hours × agreed rate per trade (e.g., $85/hr for electrician, $65/hr for apprentice)
• Materials: Actual cost + markup (typically 10-20%)
• Equipment rental: Actual cost passed through, sometimes with markup

Always agree on T&M rates before work starts, and include them in your contract.

Unit Pricing

Bill based on measured quantities of installed work: per linear foot of pipe, per square foot of flooring, per fixture installed. Unit pricing is common in:

• Landscaping (per square yard of sod, per tree planted)
• Flooring (per square foot installed)
• Plumbing (per fixture)
• Concrete (per cubic yard)

Fixed-Price (Lump Sum)

A single agreed price for the entire scope. Common for smaller residential projects where the scope is well-defined: bathroom renovation, kitchen remodel, deck build. Bill in installments tied to milestones.

Essential Elements of a Contractor Invoice

Every contractor invoice should include these elements:

Standard Invoice Fields

• Your business name, address, license number, and contact info
• Client name and project address (project address may differ from billing address)
• Invoice number (sequential, no gaps)
• Invoice date and payment due date
• Payment terms

For a detailed walkthrough of basic invoice elements, see our how to write an invoice guide.

Contractor-Specific Fields

• Project name and number — especially for commercial work
• Contract number — reference to the executed contract
• Purchase order number — if the client issued a PO
• Period covered — the billing period (e.g., "Work performed Feb 1-28, 2026")
• Schedule of values — the line-item breakdown of contract amounts
• Change order reference — any approved change orders billed in this period
• Retention amount — the percentage withheld (shown separately)
• Materials stored — materials purchased and stored but not yet installed
• Insurance/bond information — certificate numbers if required

Supporting Documentation

Attach or reference these with your invoice:

• Lien waiver — conditional waiver for the current payment, unconditional for previous payment
• Proof of insurance — current COI (Certificate of Insurance)
• Change order approvals — signed change orders for any additional work billed
• Daily logs or time sheets — for T&M work
• Material receipts — for cost-plus or T&M billing
• Photos — progress photos documenting completed work

Handling Retention (Retainage)

Retention is a percentage (typically 5-10%) withheld from each progress payment as security until the project is substantially complete. Here's how it works:

During the project: 10% is withheld from each payment application. On a $50,000 payment, you receive $45,000 and $5,000 goes into retention.

At substantial completion: You submit a request for release of retention. The owner or GC inspects the work, creates a punch list, and releases retention once punch list items are complete.

Retention laws vary by state/country. Many US states have laws limiting retention percentages and requiring timely release. Check your state's requirements — in California, for example, retention is limited to 5% on public works projects.

Tips for Managing Retention

• Track retention amounts on every invoice so there's no dispute about the total owed
• Submit your retention release request promptly at substantial completion
• Complete punch list items quickly — every day of delay is another day your retention is held
• Include retention release terms in your contract (e.g., "Retention released within 30 days of substantial completion")

Change Orders and How to Bill Them

Scope changes are inevitable in construction. A change order is a formal amendment to the contract that documents additional, deleted, or modified work along with the cost and schedule impact.

Change Order Invoicing Process

1. Document the change — written description of the work change and reason
2. Price the change — labor, materials, equipment, markup, and schedule impact
3. Get written approval — never proceed without a signed change order
4. Bill the change — reference the change order number on your invoice as a separate line item

Never perform work on a verbal "go ahead" without a signed change order. This is the single biggest source of payment disputes in construction.

Materials Markup and Pass-Through Costs

Contractors typically mark up materials 10-20% above cost. This covers:

• Time spent sourcing and procuring materials
• Delivery coordination
• Waste and breakage allowance
• Warranty administration

On your invoice, show materials either as a lump sum per line item or itemized with cost and markup shown separately, depending on your contract requirements.

For equipment rentals, fuel, permits, and other pass-through costs, bill at actual cost unless your contract specifies otherwise.

Payment Terms for Contractors

Construction payment terms are typically longer than other industries. Standard terms:

For a comprehensive breakdown of all payment term options, see our payment terms guide.

"Pay-When-Paid" vs. "Pay-If-Paid"

Many subcontract agreements include "pay-when-paid" clauses, meaning the GC pays you when they receive payment from the owner. The legal enforceability and interpretation varies by state:

• Pay-when-paid: Generally treated as a timing mechanism, not a condition. The GC must pay you within a reasonable time even if the owner is slow.
• Pay-if-paid: Shifts the risk of owner non-payment to the subcontractor. Some states have limited or banned these clauses.

Review your subcontract carefully and negotiate these terms before signing.

Protecting Your Right to Payment

Preliminary Notices

In many states, subcontractors and suppliers must file a preliminary notice within a specified period (often 20 days) after first providing labor or materials. Missing this deadline can forfeit your lien rights. File preliminary notices on every project — even if you trust the GC.

Mechanic's Lien Rights

If you're not paid, a mechanic's lien allows you to place a claim against the property you improved. Requirements vary by state, but generally:

1. You must have a direct contract (or have filed a preliminary notice for sub-tier)
2. You must file the lien within the statutory deadline (30-90 days after project completion in most states)
3. You must enforce the lien through legal action within a specified period

Consult your state's lien statutes or a construction attorney. The Construction Financial Management Association maintains resources on payment protection.

Prompt Payment Acts

Federal and many state prompt payment acts require timely payment on construction projects, especially public works:

• Federal (Miller Act): Applies to federal construction projects over $100,000
• State acts: Most states have prompt payment legislation with specific timelines and penalty interest rates

Common Contractor Invoicing Mistakes

Not billing regularly. Submit invoices on a consistent schedule (monthly is standard). Irregular billing creates cash flow gaps and makes it easier for clients to deprioritize your payments.

Missing change order documentation. Extra work without a signed change order is work you may never get paid for.

Incorrect retention calculations. Track retention meticulously on every invoice. Discrepancies lead to disputes at project close-out.

Vague descriptions. Especially on T&M invoices — log hours by task, not just "labor." Show what was done, by whom, and for how long.

Late lien filings. Deadlines for preliminary notices and lien filings are strict. Miss them and you lose your strongest collection tool.

Not keeping copies of everything. Every invoice, change order, lien waiver, daily log, and communication should be saved. Construction disputes can surface years after project completion.

Digital Tools for Contractor Invoicing

Paper invoices and spreadsheets work for a sole operator doing residential service calls. Beyond that, you need digital tools:

For creating professional invoices quickly: InvoiceQuickly generates contractor invoices from plain-English descriptions. Describe the project, billing period, and amounts, and get a professional PDF in seconds.

For progress billing templates: Use our invoice templates and customize them for your schedule of values format.

For payment tracking and follow-up: Automated reminders ensure you follow up on overdue payments without it feeling personal. Our payment reminder tool drafts professional collection emails.

For late fee calculations: When invoices go overdue, use our late fee calculator to determine the correct interest amount based on your contract terms and applicable law.

Get Paid Faster on Every Project

Contractor invoicing doesn't have to be complicated. Set up your schedule of values, bill consistently on schedule, document every change order, track retention carefully, and follow up on late payments systematically.

Start with InvoiceQuickly to create professional contractor invoices in seconds. Describe the project and billing details in plain English, and get a complete, professional invoice ready to submit. Create your first contractor invoice now.