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How to Create an Invoice: The Complete Guide for Freelancers

2026-07-14 · 7 min leestijd

Creating an invoice looks more complicated than it actually is, as long as you know which details are mandatory and which approach fits your situation. Just starting out as a freelancer? A simple template in Word or Excel is often all you need. Selling through your own webshop or via marketplaces? You'll quickly want invoices to create themselves. This guide walks through every option — from typing it out by hand to full automation — with a concrete step-by-step plan and examples.

What Must Legally Be on an Invoice?

An invoice is only a valid invoice once it includes a set of mandatory details. Leave something out, and the Belastingdienst (the Dutch Tax Authority) can refuse the VAT deduction for you or your client. At minimum, an invoice needs:

• your VAT identification number and KVK (Chamber of Commerce) number
• a sequential invoice number, with no gaps or duplicates
• the invoice date
• your name and address, and your client's
• a clear description of the products or services delivered
• the amount excluding VAT, the VAT rate and VAT amount, and the total amount including VAT

Do you work under the KOR (the Dutch small businesses scheme) or supply something that's exempt from VAT, such as certain education or healthcare services? Then you send a VAT-free invoice. In that case, state the reason for the exemption on the invoice, for example 'invoice exempt from VAT under the KOR'. If you're unsure which rules apply to your situation, check the current requirements on Belastingdienst.nl before you send your first invoice.

Would rather not chase down loose invoices in your inbox? Make sure every invoice you create automatically lands in the same overview. That saves you the hassle when you file your VAT return or a client asks for a copy.

Sample Invoice for Freelancers: What Does a Good Invoice Look Like?

A sample invoice for a sole proprietorship or any other freelancer always follows the same basic structure, even if the exact layout differs from program to program. Your business details and logo sit at the top, followed by your client's details and the invoice number with the date. Below that come the invoice lines: description, quantity, unit price, VAT rate, and line total. At the bottom, you close with the subtotal, the VAT, and the grand total, plus your payment terms and IBAN.

Looking for a ready-made sample invoice in PDF, Word, or Excel? Make sure the format already includes all the mandatory details and that you can easily adapt it to your own branding. Invoicing without VAT under the KOR or an exemption? Use the same template — just leave the VAT line blank and state the exemption reason at the bottom.

Not keen on downloading and filling in a template by hand every time? With a template designer, you set your logo, colors, and layout once, and it's applied automatically to every invoice from then on — something slimzaak is built specifically for freelancers to handle.

Creating an Invoice in Word or Excel

Plenty of freelancers start out creating invoices in Word or Excel. That makes sense: you probably already have the software, it costs nothing extra, and you control the entire layout yourself.

The downsides show up once you send more than a few invoices a month:

• you keep track of sequential numbering by hand, and sooner or later that goes wrong
• there's no automatic check on mandatory details, so if you miss something, you often only find out when you file your VAT return
• you archive everything yourself, even though invoices legally have to be kept for 7 years
• an address or price change means updating every invoice one by one
• no link to your bank or webshop, so you check payments and shipments manually

For a single invoice a month, an Excel or Word template works fine. But once your admin grows, or you sell through multiple channels, manual work quickly becomes error-prone. Curious which accounting software fits better than loose files? We've lined up the options for freelancers.

One in-between step a lot of freelancers skip: a standalone invoicing tool with no link to your bookkeeping. That's just as manual as Word or Excel, only with a fixed layout. For invoicing on a regular basis, you really only save time once invoicing, payments, and your VAT overview come together in a single system.

Creating a Free Invoice Online

Beyond Word and Excel, there are dozens of free invoice-maker apps: you fill in a form and download a PDF straight away. Handy for a one-off invoice, for example right after you start your business or if you only invoice occasionally.

The limitations surface once invoicing becomes a regular thing:

• invoices usually aren't saved in any kind of overview, so you have to hunt them down individually when it's time for your VAT return
• no sequential numbering across multiple invoices
• no link to clients, products, or earlier quotes, so you keep retyping the same details
• often limited or no support for multiple VAT rates, the OSS scheme, or credit notes for returns

Want to invoice online for free, but with a complete overview, sequential numbering, and an archive? Then look at invoicing software with a genuinely free plan, rather than a standalone generator. slimzaak's free ZZP plan, for example, gives you up to 250 invoices a month, your own invoice templates, and one store connection, no credit card required.

Switching to invoicing software might feel like overkill at first for 'just a few invoices'. In practice, the difference shows up most clearly at VAT return time: all your revenue and VAT are already sorted and ready, instead of you hunting down loose PDFs.

Automatically Generating Invoices

Selling through your own webshop or via marketplaces like bol.com, Amazon, Shopify, or WooCommerce? Then every order is a new invoice you really don't want to type out by hand. With automatic invoicing, you connect your store once, and the system creates an invoice for every new order from then on — with the correct VAT rate, the OSS scheme applied for EU sales, and in your own branding.

Get a return? slimzaak automatically issues a credit note, instead of you correcting it yourself. Sell through multiple channels at once, say your own shop plus a bol.com connection, and every order flows into a single, continuous invoice numbering sequence. That means you'll never end up with duplicate or skipped numbers.

You start for free, with up to 250 invoices a month and one manually connected store. Want to invoice automatically per order? Switch to a paid plan starting at €9 a month. That way, you never have to create an invoice by hand again once your store grows.

Creating an Invoice Yourself in 5 Steps

Prefer to create an invoice yourself, step by step? Here's how:

1. Gather your details. Client name and address, your own VAT and KVK number, and a clear description of what you delivered.
2. Set the invoice number and date. Use a sequential series, for example 2026-001, 2026-002, without skipping numbers.
3. Work out the invoice lines. Quantity, unit price, VAT rate, and line total, for each product or service separately.
4. Calculate the total. Subtotal excluding VAT, the VAT amount per rate, and the grand total including VAT.
5. Check and send. Verify the mandatory details, save the invoice to your archive, and send it as a PDF to your client.

Did you start with a quote? Convert it into an invoice with a single click instead of retyping everything, so amounts and descriptions stay consistent. Want to know more about putting together a solid quote? Also check out our article on creating a quote as a freelancer.