Progress Billing for Contractors: A Worked Invoice Example

Progress billing means invoicing only the value of work completed at a defined stage or measured point in the job, while showing a separate running summary of the whole contract. For contractors, the most common mistake is mixing up four different figures: the total contract value, previously invoiced, the current invoice amount, and outstanding unpaid amounts on earlier invoices. They are connected, but they are not the same number.

A clear progress invoice keeps the current charge limited to the work billed now, then uses a cumulative summary to show how that invoice fits into the larger project. If you want a starting layout, a contractor invoice template for staged work can help you enter line items, tax and currency settings, payment instructions, and manually entered previous billing details before generating a PDF.

The arithmetic that keeps progress billing accurate

Treat the project like a running ledger. Each invoice should separate:

• Original contract
• Approved changes added or deducted
• Revised contract total
• Previously invoiced
• Current invoice
• Total invoiced after this invoice
• Payments received to date
• Outstanding on issued invoices
• Unbilled remaining value

Two quick checks catch many errors:

1. Previously invoiced + current invoice = total invoiced after this invoice
2. Total invoiced after this invoice - payments received = outstanding on issued invoices

That second check matters because an invoice is not proof of payment. Payment status should be matched to actual payment records, not assumed from what was sent. The IRS says businesses should keep a recordkeeping system that clearly shows income and expenses and retain supporting records: IRS business recordkeeping guidance.

Worked example: cumulative project ledger before the new invoice

Assume a fictional residential installation contract in USD, with tax excluded for illustration because actual tax treatment varies by situation.

• Original contract: $24,000
• Approved change orders so far: $0
• Revised contract total: $24,000

The billing schedule is:

• Stage 1: site preparation
• Stage 2: rough installation
• Stage 3: finish and handover

Here is the billing history before the next invoice:

Before creating the new invoice, the project position is:

• Revised contract total: $24,000
• Previously invoiced: $15,500
• Payments received to date: $14,000
• Outstanding on already issued invoices: $1,500
• Unbilled remaining value before current invoice: $8,500

That last figure is often misunderstood. It is not the amount due now. It is only the portion of the contract that has not yet been invoiced.

The actual current invoice lines

The next billing event is completion of the main rough installation stage. The contractor decides to invoice only the value earned in this billing event, not the whole remaining contract.

• Invoice number: INV-304
• Project reference: Q-301
• Currency: USD
• Tax: excluded for illustration

Suggested invoice lines:

• Current invoice subtotal: $5,500
• Tax: $0 in this fictional example because tax is excluded for illustration
• Amount due on this invoice: $5,500

Then add a clearly labeled project summary on the invoice or on an attached statement:

The key point is simple: the amount due on INV-304 is $5,500, not $7,000. The $7,000 figure includes the older unpaid balance from INV-303.

How to show previous billing without double charging

Do not fold unpaid old amounts into the current line items as if they were new work. That makes the invoice harder to read and can create a double-billing dispute.

A cleaner structure is:

• keep the current invoice lines for current work only
• show previously invoiced as a separate cumulative figure
• show payments received based on actual receipts
• list older unpaid invoices in a note or statement section by invoice number

For example:

Project summary: previously invoiced $15,500. Payments received to date $14,000. One earlier balance remains unpaid: INV-303 $1,500. Current invoice INV-304 is $5,500.

That wording separates three things customers often confuse: the new charge, any older unpaid amount, and the overall project position. If you want a practical format, start with a contractor invoice template with room for stage descriptions and add the cumulative summary manually.

Common mistakes in progress invoices

A few arithmetic errors show up repeatedly.

Invoicing the whole contract again. If the contract is $24,000, the fourth invoice should not demand $24,000 unless it is somehow the first and only invoice.

Subtracting payments instead of prior billings. What you can bill now depends on work already invoiced, not whether prior invoices have been paid. Late payment does not increase earned value.

Confusing outstanding totals with the current invoice amount. In the example, $7,000 is outstanding across issued invoices, but only $5,500 belongs on the new invoice.

Deducting a deposit twice. If an earlier deposit was already invoiced and included in previously invoiced totals, do not subtract it again unless your contract requires a separate credit presentation.

Ignoring approved changes. If the scope changes, revise the contract total first. For a focused example on that issue, see How to Invoice Approved Change Orders.

Two real edge cases contractors run into

Partial payment on an earlier invoice

This is already happening in the worked example. INV-303 was issued for $4,000, but only $2,500 has been received so far. The next progress invoice should still bill the newly earned work correctly.

That means:

• the current invoice reflects current earned work only
• the earlier $1,500 shortfall stays attached to INV-303
• the cumulative summary shows total outstanding across issued invoices

Do not reduce the new invoice just because the customer is behind, and do not increase it to absorb the arrears.

Approved change order during the project

Assume a $1,200 change order is approved after INV-303 but before INV-304.

Then the project totals become:

• Original contract: $24,000
• Approved changes: $1,200
• Revised contract total: $25,200
• Previously invoiced: $15,500
• Current invoice: $5,500
• Total invoiced after current invoice: $21,000
• Unbilled remaining value: $4,200

The important correction is to update the contract total, not to hide the change inside a vague line such as “balance remaining.” If you are still planning stage payments, Contractor Payment Schedule: Deposits, Milestones and Final Payment covers that part of the job.

A clear summary block you can reuse

You do not need legalistic wording to make a progress invoice understandable. Plain language is usually better.

This invoice covers the current project stage completed under contract reference Q-301. Revised contract total: $24,000. Previously invoiced: $15,500. Current invoice: $5,500. Total invoiced after this invoice: $21,000. Payments received to date: $14,000. Outstanding on issued invoices after this invoice: $7,000.

That summary keeps the total contract, previous billings, current invoice, and unpaid amounts in separate lanes. It also makes review easier before you send the PDF.

On the document side, InvoiceSonic supports creating an invoice with business and client details, line items, tax and currency settings, payment instructions, a PDF, saved client details and accounts, invoice status tracking, and reminders subject to settings and plan limits. Operational records such as approval logs, site evidence, and payment matching still need to be maintained separately in your own workflow. If you want to compare account options, see pricing.