# Invoicing in Excel: when it stops working and how to move on

Source: https://lucanto.eu/blog/invoicing-in-excel
Author: Erich Stark
Published: 2026-09-14

Invoicing in Excel stops being enough once you are keeping track of things a spreadsheet cannot check for you: whether the numbering runs unbroken, whether the customer details are right, and which invoice has actually been paid. Moving to an online tool takes minutes — set up your company, continue the number series, import your contacts and issue your first invoice.

import Figure from '../../../components/article/Figure.astro';
import excelShot from '../../../assets/images/blog/invoicing-in-excel/en/excel.png';
import lucantoShot from '../../../assets/images/blog/invoicing-in-excel/en/lucanto.png';

Invoicing in Excel is a perfectly sensible way to start. Nobody issues their first invoice in a piece of software — they open a spreadsheet, type the details in and send a PDF. The problem is not that it does not work. The problem is that a spreadsheet never tells you when it has stopped working.

This guide is about spotting that moment and what to do about it.

## When invoicing in Excel stops being enough

It is not about how many invoices you send. It is about how much you are now keeping track of in your head. Five signs, and they tend to arrive together:

- **You copy the last invoice and overwrite it.** That means your "system" is the most recent file — and whatever you missed in it gets copied along with everything else.
- **You have to check which number comes next.** A number series is meant to run unbroken. When you are not sure, it is no longer you keeping it that way.
- **You cannot say off the top of your head who owes you.** A spreadsheet records what you issued. Not what arrived in your account.
- **You retype client details out of an email.** A typo in a company number or an address only surfaces on a document that has already gone out.
- **Your accountant sends documents back.** That is the most expensive sign, because it arrives a month late.

If two or more of those landed, Excel is no longer a tool. It is overhead.

## The same invoice in a spreadsheet

Here is an ordinary invoice in a spreadsheet. Two line items, 23 % VAT, 1 586,70 € in total.

<Figure
  src={excelShot}
  alt="An invoice in a spreadsheet: cells holding the supplier and customer details, two line items, and a VAT row containing a hand-written formula."
  caption="You write the formula in the VAT row yourself — and you are the only one checking it."
  sourceScale={1}
  eager
/>

It works. But notice how much of it is held together by your attention alone: the `=F18*0,23` in the VAT cell, an invoice number typed by hand, a customer VAT ID with nothing to check it against. The spreadsheet verifies none of it.

## The same invoice in a tool

<Figure
  src={lucantoShot}
  alt="The same document in Lucanto: line items in a table, VAT calculated on each row, and a summary showing the taxable amount and the VAT separately."
  caption="The same two line items. The tool works out the taxable amount and the VAT, and the total follows."
  sourceScale={1}
/>

Same numbers, different division of labour. You pick the rate rather than compute it; the summary separates the taxable amount from the VAT; the number is assigned from the series on issue, so it is not yours to watch.

## What actually changes

The difference is not that the invoice looks nicer. It is what the tool keeps track of instead of you.

|                         | Excel / paper   | Online tool                        |
| ----------------------- | --------------- | ---------------------------------- |
| Company details         | you retype them | filled in from the public register |
| Number series           | you watch it    | runs on automatically              |
| VAT registration check  | none            | built in                           |
| Payment overview        | kept separately | status sits on the document        |
| Access to your invoices | one computer    | any browser, anywhere              |

The register lookup covers Slovak and Czech companies — you enter the company number and the name, address and VAT ID fill themselves in. For a client in another country you enter them once by hand and the tool remembers them.

## The move, step by step

Migrating sounds more frightening than it is. From signing up to your first issued invoice is a matter of minutes, and you do not have to lose a single old document.

### 1. Set up the company and continue the number series

Upload a logo, fill in your company details and a bank account. Then the part that matters: set the number series to continue from the last number you issued in Excel — the **First number of series** field does it, and the [number series guide](/guides/number-series) walks through the whole setup. This is the one step worth doing carefully — a number series should be unbroken, and you cannot renumber documents that have already gone out.

### 2. Move the contacts, not the history

Your client list uploads from Excel in one go, instead of being retyped. Old invoices do not need to come with it — they are issued and archived where they are. What belongs in the tool is what you will use from here.

### 3. Issue a test invoice to yourself

Before the first real document goes out, invoice yourself. You will see exactly what the client sees: the logo, the number, the layout, and how it arrives by email. If you want to check what has to be on the document, see [how to issue an invoice](/blog/how-to-issue-an-invoice).

### 4. Agree the handover with your accountant

Ask what format they want the records in before you send them a first month. On the higher plans (PRO and Business) you can invite them straight into the system and you both see the same data; otherwise you hand over an export. Agreeing this up front saves a month of back-and-forth before the deadline.

## What to bring across, and what to leave

The most common migration mistake is trying to bring everything.

**Bring:** your client list, your own company details, the number series format and its last value, and any line items you invoice repeatedly.

**Leave:** invoices already issued, pricing workings, project notes. The archive of past years has its value exactly where it is — as a record that does not change. Retyping it into a new tool so that everything is "in one place" is work with no result.

## What the first month looks like

The first two or three documents will take longer than they did in Excel. You are still finding where things are, and that is normal. From the fourth onwards it is quicker, because the clients and the line items are already in the system and an invoice is assembled by picking, not typing.

Worth checking in that first month:

- **That the numbering lines up** — check the first document against the last one from Excel.
- **How the document looks to the client** — open your test invoice on a phone, not just on a monitor.
- **What the Free plan covers** — unlimited one-off invoices, 50 clients, register lookup, a payment QR code on the invoice, invoices in another language and another currency, the VAT registration check and one bank account. You cannot send the document from Lucanto itself on Free — you download it as a PDF. The details are on [free invoicing](/free-invoicing).

The things a growing business needs — AI extraction from an uploaded document, quotes and advance invoices, sending straight from Lucanto, recurring invoices, bank matching over PSD2, or inviting your accountant into the system — sit on the paid plans. Which is on which is set out in the [pricing](/pricing).

One more thing worth saying plainly: a mobile app that photographs receipts, automatic payment reminders and full e-invoicing over Peppol are still in preparation at Lucanto, not finished. If another tool promises you one of those, check whether it exists or is only marked "coming soon".