Odoo 18 · Accounting · Invoicing

How to create an invoice in Odoo 18 step by step

A practical beginner guide to create customers and invoices in Odoo 18, with the ERP/CRM difference made clear.

Once Odoo is installed, one of the first real business tasks is issuing the first invoice correctly. This guide explains the manual flow from zero: create or choose the customer, add the product or service, review the invoice lines, post the invoice, send it and register the payment.

Before clicking New invoice, it helps to understand where each piece belongs: the CRM manages the commercial relationship before the sale; the ERP records the operational and accounting reality after the sale.

If you still do not have Odoo running on your server, start with the installation guide first: install Odoo 18 on AWS EC2 with Ubuntu 24.04.

From customer data to payment registration, all in a single invoice flow.

Where to create the invoice in Odoo 18

In Odoo 18, the usual manual route is Accounting > Customers > Invoices > New. Then you select the customer, add invoice lines, check taxes and payment terms, click Confirm and, if needed, Register Payment afterwards.

1. Before creating the invoice

The minimum requirement is to have the Accounting or Invoicing app available and basic company data configured. For a first test you do not need a complex setup, but these elements should already exist:

Your company is configured with the correct currency and tax environment.
You have at least one customer contact.
You have at least one product or service to bill.
Your sales journal and invoice sequence are active.

Practical note: for a quick first invoice, a service product is often easier than a stocked product, because you avoid delivery and inventory details.

2. ERP vs CRM in Odoo: what is the difference?

Odoo can be used as both CRM and ERP, but they do not solve exactly the same problem. The CRM is focused on the sales relationship before the customer buys: leads, opportunities, calls, activities, quotations and pipeline. The ERP is broader: it connects sales, invoices, accounting, inventory, purchases, projects and operations.

CRM

Helps you manage commercial work before the sale: who the prospect is, what they need, what activity is pending and whether the opportunity is moving through the pipeline.

Leads and opportunities.
Sales pipeline and activities.
Quotations and follow-up.

ERP

Helps you manage the business process after and around the sale: customer master data, invoices, payments, taxes, accounting entries, stock and reporting.

Contacts, products and invoices.
Accounting and payment reconciliation.
Inventory, purchases and operational data.

Simple rule: if you are deciding whether a prospect may become a customer, you are in CRM territory. If you are issuing an invoice, registering a payment or reporting taxes, you are in ERP territory.

3. How to create the customer before invoicing

In Odoo, a customer is normally a contact that later appears in sales, invoicing and accounting. You can create it from Contacts > New, from Sales > Customers, or directly from the customer field while creating an invoice. For a clean database, creating the contact properly before invoicing is usually better than improvising it from the invoice form.

Go to Contacts > New.
Choose whether the customer is a Company or an Individual.
Fill in legal name, VAT/tax ID if applicable, invoice address, email and phone.
Add child contacts or addresses if billing, delivery and contact person are different.
Review the Sales & Purchase and Accounting tabs if your setup uses payment terms, fiscal positions or specific accounts.

The key idea is that the customer record is not only an address book entry. Odoo can reuse that data to fill the invoice address, payment terms, fiscal position, receivable account and communication preferences.

FieldWhy it matters

Company / IndividualDefines how the contact is represented and how related addresses or people are organized.

Tax ID / VATImportant for legal invoicing, fiscal positions and customer identification.

Invoice addressPrevents sending the invoice to the wrong legal or administrative address.

Payment termsControls the due date automatically when the invoice is created.

4. Product or service data you should have ready

Odoo fills many fields automatically from the customer record. That means the contact should already have clean billing information, and the product or service should have the expected sales price and taxes.

Main fields to check before confirming an invoice in Odoo 18 — Main fields that matter before you confirm the invoice.

Customer: billing address, payment terms and fiscal data should be coherent.
Product or service: name, unit price and taxes should already be correct.
Journal: usually auto-filled, but worth checking.
Due date or payment terms: define when the invoice should be paid.

5. How to create the invoice manually in Odoo 18

Go to Accounting > Customers > Invoices and click New. Odoo opens the draft invoice form. From there, the usual sequence is simple and very repetitive, which is exactly what you want in day to day invoicing.

Invoice lifecycle in Odoo 18 from draft to paid — The status flow usually goes from Draft to Posted and finally Paid.

Select the customer.
Review invoice date and due date or payment terms.
Add one or more invoice lines.
Check quantities, unit prices and taxes.
Review totals before posting.

If you already work from sales orders, Odoo can also create invoices from the sales flow, but for learning the basics, doing the first one manually is usually clearer.

CRM to ERP flow: in a more complete sales process, the opportunity lives in CRM, the quotation or sales order lives in Sales, and the customer invoice lives in Accounting. The same customer connects all those steps.

6. Confirm, send and register payment

While the invoice is still in Draft, you can edit it freely. Once everything looks right, click Confirm. Odoo moves the invoice to Posted status and creates the corresponding accounting entry.

Use Send if you want to email it to the customer.
Use the print or PDF options if you need to review the layout first.
Use Register Payment when the customer has paid and you want to reflect it in Odoo.

The invoice is considered fully paid when the accounting side is properly reconciled. For a first manual test, registering the payment directly from the invoice screen is the fastest path.

7. Common mistakes when creating a first invoice in Odoo

Using a customer without complete billing details.
Confusing CRM activity with accounting work: a lead is not yet an invoiceable customer process.
Posting the invoice without checking taxes.
Editing the wrong price because the product record was not configured first.
Forgetting payment terms and then getting the due date wrong.
Trying to modify a posted invoice instead of resetting it to draft when appropriate.