How to Create an Invoice: A Step-by-Step Guide for New Entrepreneurs

Once you get your first clients, it’s time to prepare your first invoice.

An invoice is not just a piece of paper or a PDF. It is an official confirmation that one party has delivered a product or service, and the other has agreed to pay for it.

At first, creating an invoice may seem complicated, but in reality, it is a straightforward process.

When you know what information to include and how to structure it, invoicing quickly becomes an easy routine.

What information must be on an invoice?

Every invoice must include at least the following details:

• Invoice number – unique and following a logical sequence

• Date of issue

• Seller’s details – company name, registration number, address, bank account

• Buyer’s details – client’s name, registration number, address

• Description of goods or services – what was sold and in what quantity

• Price – excluding VAT

• Value-added tax (24%) – only if you are VAT registered; show both the rate and the amount separately

• Total amount payable – including VAT

• Payment due date

• Company bank account number
  
  

If all these fields are present, your invoice will be properly formatted and easy for the client to process.

How to choose your invoice number

Each invoice must have a unique number.

The easiest way is to decide on a numbering system that fits your company and follow it consistently.

Common formats include:

• Year + serial number (26001, 26002 …)
  
  

• Year + shorter number (2601, 2602 …)
  
  

• Date + serial number (01012601)
  
  

Consistency helps you stay organised and avoid duplicate invoices.

Step-by-step: how to create an invoice

1. Choose your tool.
   For small volumes, Excel or Google Sheets is enough.

 If you issue more invoices, use free tools such as E-arveldaja or Banqup.

For higher volumes, paid software like Merit Aktiva, SimplBooks or Directo offers more features and integrations.

2. Add the invoice number and date.
   
   Follow your chosen numbering system and enter the issue date.
   
   

3. Enter seller details.
   
   Company name, registration code, address, bank account.
   
   

4. Add client details.
   
   Company or individual name, registration code, address.
   
   

5. Describe the service or product.
   
   Make it clear and easy to understand.
   
   For example: “Marketing service, September 2025 – 5 hours” or “Office chairs, 3 pcs.”
   
   

6. Add prices.
   
   Show the price excluding VAT, the VAT (24%) separately, and finally the total including VAT.
   
   

7. Include payment information.
   
   Bank account number and payment deadline.
   
   

8. Check everything.
   
   Make sure all data is correct and that the invoice number is unique.
   
   

Example Invoice

Invoice No: 25001

Date: 20.09.2025

Seller: OÜ Sample Company

Reg. code: 12345678

Address: Tallinn

Bank account: EE123456789012345678

Buyer: OÜ Client Company

Reg. code: 87654321

Address: Tartu

Service description: Graphic design service

Quantity: 1

Unit price: €200

VAT (24%): €48

Total amount: €248

Payment due date: 04.10.2025

Where to create invoices

• Excel or Google Sheets – suitable for beginners and small businesses
  
  

• Free invoicing platforms – E-arveldaja, Banqup
  
  

• Paid software – Merit Aktiva, SimplBooks, Directo and others with extra features and integrations
  
  

How long should invoices be kept?

Creating invoices is only half of the process.

It is equally important to store them correctly.

In Estonia, invoices must be kept for at least seven years after the end of the financial year in which they were issued.

Example:

If you issued an invoice in 2025, you must keep it until 2032.

Invoices can be stored either on paper or digitally. What matters is that they can be found and accessed quickly if needed.

Frequently Asked Questions

Can I make an invoice in Word or PDF?

Yes. The format does not matter as long as all required information is included.

Does a sole proprietor (FIE) have to issue invoices?

Yes. The rules for invoicing are the same as for private limited companies (OÜ).

Does an invoice need a signature?

No. A digital invoice without a signature is fully valid.

What if a client does not pay on time?

Start with a polite reminder.

If the client still does not respond, you can forward the unpaid invoice to a debt collection agency (inkasso).

Summary

Creating an invoice is not difficult.

Once you have a simple numbering system and know what details must be included, invoicing becomes a natural part of your daily business.

In the beginning, it may feel time-consuming, but soon you will find your rhythm and start preparing invoices as easily as your morning coffee.

And finally, sending an invoice is not just a formality.

It is a small celebration that shows your company is growing and your work is paying off.