Most people think an invoice is an invoice. Then a client asks for a proforma, an accountant mentions a credit note, and a shipping company wants a commercial one. Knowing the main types of invoices saves you from sending the wrong document at the wrong moment.
This guide walks through each type in plain language, shows when to use it, and covers the payment terms and formats that apply to all of them. If you need the basics first, start with our guide on what an invoice is and what it must include.
The types of invoices at a glance
An invoice is a document a seller sends to a buyer, listing what was supplied and requesting payment. The invoice definition stays the same across all types. What changes is the purpose: billing for completed work, announcing a future sale, repeating a charge, or fixing a mistake.
Here is a quick comparison before we go deeper.
| Type | Used for | Requests payment? |
|---|---|---|
| Standard invoice | Work or goods already delivered | ✅ |
| Proforma invoice | Quoting a sale before it happens | ➖ Advance only |
| Commercial invoice | International shipments and customs | ✅ |
| Recurring invoice | Retainers, subscriptions, rent | ✅ |
| Interim invoice | Long projects billed in stages | ✅ |
| Credit note | Cancelling or reducing a previous invoice | ❌ |
The three types of invoices most people mean
When someone asks for the three types of invoices, they usually mean the standard invoice, the proforma invoice and the credit note. These three cover the full life of a simple sale: you quote it, you bill it, and sometimes you correct it.
Standard invoice
This is the everyday one. You did the work or delivered the goods, and now you ask to be paid. It carries your details, the client's details, a unique invoice number, the date, a description of what was supplied, the amounts and the payment terms.
A simple invoice for a freelancer is just this, nothing more. One client, one job, one total.
Proforma invoice
A proforma invoice is a preliminary document sent before the sale is final. It tells the buyer what the invoice will look like, often so they can arrange funding, a purchase order or an import licence. It is not a tax invoice and usually does not count as a payment request in your accounts.
The proforma invoice meaning trips people up because it looks almost identical to a standard invoice. The difference is intent. For a fuller walkthrough, read our proforma invoice guide.
Credit note
A credit note, sometimes called a credit memo, cancels or reduces an invoice you already issued. Use it when you billed too much, when goods came back, or when a service was not delivered in full. Never edit a sent invoice. Issue a credit note that references the original number, then issue a new invoice if needed.
Different types of sales invoices
Beyond the big three, a handful of sales invoices show up regularly. Which ones matter depends on what you sell and where your clients are.
Commercial invoice
A commercial invoice accompanies goods crossing a border. Customs uses it to work out duties and taxes, so it needs a precise description of the goods, quantities, unit prices, the country of origin and the terms of sale. If you only sell services domestically, you will probably never need one.
Recurring invoice
Recurring invoices repeat on a schedule: a monthly retainer, a hosting fee, a weekly cleaning contract. The content barely changes, so the saving comes from automation. Each one still needs its own number and date, and you should confirm the amount before it goes out if the scope has shifted.
Interim and final invoices
On a long project, waiting until the end to bill is a cash flow trap. Interim invoices split the fee into milestones, such as 30% at kickoff, 40% at delivery of a draft and 30% at completion. The final invoice then settles the balance and should show what was already paid.
Past due and timesheet invoices
Two more variants come up in practice. A past due invoice is simply a reminder version of an unpaid standard invoice, often with a late fee added if your terms allow it. A timesheet invoice lists hours worked and the hourly rate, common for contractors and consultants.
Invoice payment terms: what to put on every type
Whatever type you send, the payment terms decide how fast you get paid. They are a short block of text, but they carry weight if a client disputes the bill.
The usual elements are:
- Due date or period. "Due on receipt", "net 14" or "net 30" are the most common. Net 30 means payment is expected within 30 days of the invoice date.
- Accepted payment methods. Bank transfer details, card link or another method you actually support.
- Late payment terms. A fixed fee or interest rate, if your contract and local law allow it.
- Early payment discount. For example, 2% off if paid within 10 days. Use it sparingly, since it cuts your margin.
Shorter terms tend to get you paid sooner. Longer terms win clients who run slow accounts payable processes. Pick what your cash flow can survive, then state it clearly. Rules on late payment interest and maximum payment periods differ by country, so check the rules that apply to you or ask your accountant.
Different types of invoice formats
The word "format" gets used for two things. Sometimes people mean the file type. Sometimes they mean the layout and data structure. Both matter.
File and delivery formats
- PDF by email. The default for freelancers. Easy to send, hard to alter.
- Word or spreadsheet files. Fine to start with, but easy to break and awkward to track.
- Paper. Still used for in-person trades and some local businesses.
- Invoice software and apps. They number invoices automatically, store clients and track who has paid.
E-invoices
An e-invoice is not just a PDF. It is a structured digital file that software can read without human input, and several countries already require or are phasing in e-invoicing for business sales. If you invoice clients abroad, check the local rules before assuming a PDF is enough.
How to choose the right invoice
Start with one question: what has actually happened? If the work is done, send a standard invoice. If a deal is agreed but nothing is delivered, a proforma or a quote may fit better. If you made a mistake, issue a credit note. If goods cross a border, add a commercial invoice.
Then check the basics that apply to every type. Each document needs a unique number, a clear date, correct legal names and a precise description of what you supplied. Tax details depend on your country and status, so confirm what must appear with an accountant or your tax authority.
If you want a ready layout instead of building one from scratch, the free invoice template gives you a clean starting point for the standard type.
Common mistakes when mixing up invoice types
Mistakes here are rarely dramatic, but they cost time and sometimes money.
- Treating a proforma as a real invoice. Your client pays it, your accountant never sees a tax invoice, and the books get messy.
- Editing a sent invoice. Once issued, it should stay as it is. Cancel it with a credit note and start fresh.
- Reusing a recurring invoice without checking. Scope changes, rates change, and the old amount keeps going out.
- Leaving payment terms vague. "Pay soon" is not a term. Without a date, the client has no deadline to miss.
- Skipping the commercial invoice on exports. Goods held at customs because paperwork is incomplete is an avoidable delay.
Keeping a simple record of which document you sent, when and why takes five minutes a week and saves hours at tax time.
Picking the right tool for the job
You can manage all of these types with a spreadsheet, a word processor or dedicated invoicing software. The right choice depends on volume. A few invoices a month work fine with a template. Dozens, with recurring clients and credit notes, are easier in an app that handles numbering and reminders for you.
Whichever route you take, consistency matters more than sophistication. A clear, correctly numbered invoice sent promptly beats a beautiful one sent three weeks late.
Conclusion
The types of invoices are not exotic. A standard invoice bills finished work, a proforma previews a sale, a credit note fixes errors, and the commercial, recurring and interim versions cover specific situations. Match the document to what has really happened, state your payment terms plainly, and keep the numbering clean.
If you would like a simple way to create and send these documents from your phone, Voila is built for freelancers and small businesses and is coming soon to iOS. You can join the early access list to be among the first to try it.