What an online invoice is
An online invoice is not a file on your computer that happens to be a PDF. It is a document you create, send and keep in the cloud — you open a browser, fill in a form, and the tool does the parts that are easy to get wrong: the sequential number, the tax calculation, the required fields.
The practical difference shows up later rather than at the moment of issuing. The invoice is not in one laptop's folder; it is in an account you can reach from anywhere, next to every other invoice you have sent, in one unbroken numbering sequence.
Why not Word or Excel
A template does not check anything. It will let you reuse a number, leave out a required field, or mistype one digit of an account number — and none of that surfaces until the document has already gone out.
An online tool watches those for you: the number is assigned automatically, customer details come from a register where one exists, the tax is calculated rather than typed into a formula, and the finished document is in your account rather than in a folder you have to find.
This page is about what online invoicing does. If you are still invoicing in a spreadsheet and wondering how to move — including how to continue your existing numbering — that is covered in invoicing in Excel and how to move on.
| Step | What happens |
|---|---|
| 1 — the customer | Type the name or the registration number. For Slovak and Czech companies the address and tax IDs fill in from the register; elsewhere you enter them once and the tool remembers them. |
| 2 — the line items | Description, quantity, price. The tool works out the tax and the totals, and you pick the language of the document and the currency. |
| 3 — the number | Assigned from your number series on issue, so the series stays unbroken and no number is used twice. |
| 4 — sending | Download the PDF, or send it by e-mail straight from Lucanto on the paid plans. The document stays in your account either way. |
Invoice from a laptop or a phone
Because the tool runs in a browser, there is nothing to install and nothing to keep updated. You sign in from a laptop at the desk or from a phone on the way back from a job, and it is the same account with the same data.
That matters most in the gap between finishing work and invoicing for it. An invoice sent the same day tends to get paid sooner than one that waits for you to be back at a particular computer.
Invoicing abroad: currency and language
Two things decide whether a foreign client can pay you without friction — whether they can read the document, and whether the amount is in a currency that makes sense to them.
Lucanto issues the invoice in Slovak, Czech, English or Romanian, and in a foreign currency with the rate pulled from the ECB. Both are on every plan, including Free. What you do about tax on a cross-border sale is a separate question and depends on where both sides are based — that one is worth checking, or asking an accountant.
Upload a document and let AI read it
Invoicing is only half of it; the other half is what you paid out. Lucanto extracts the supplier, the amount and the date from an uploaded document, so an expense becomes a record rather than a retyping job. AI extraction is on the paid plans, from Starter up.
From a quote to a paid invoice
Work rarely starts with an invoice. It starts with a quote, sometimes an advance, and only then the invoice — and each of those normally means retyping the same details.
In Lucanto they are linked: a quote becomes an advance invoice, an advance invoice becomes the final one, and the details carry across. Quotes, advance invoices and that linked flow are on the paid plans, from Starter up; collaboration with an accountant is on PRO and Business.
Are online invoices legally valid?
Practically everywhere, yes. An electronic invoice generally carries the same weight as a paper one — that principle is settled across the EU and well beyond it.
What differs from country to country is the fine print: whether the recipient has to agree to receive it electronically, what you have to be able to guarantee about the document (typically that its origin is clear, its content unchanged and it is readable), and how long it has to be kept. A document issued in Lucanto has an identifiable issuer, is stored unchanged and is readable as a PDF — but the requirement it has to meet is the one that applies where you invoice, so check that.
Keeping invoices
Retention periods are set by national law and are usually counted in years. Because the obligation is long, where the documents live matters more than it first appears: a cloud archive is easy to produce years later, a folder on a laptop that has since been replaced is not.
Lucanto keeps your invoices in the account on every plan and adds a ten-year digital archive on PRO and Business.