An invoice with a formal error is not just a cosmetic detail: it can stop being valid as a tax record, both for you and for whoever is paying you.
The mandatory details
- A sequential invoice number, with no gaps or duplicates within the same series.
- Date of issue.
- Your full details and NIF, and your client’s: name or company name, NIF/CIF, and address if it’s a company.
- A clear description of the transaction.
- Taxable base, the VAT rate applied and the resulting amount, and, where it applies, the IRPF withholding.
- Total amount.
Common mistakes
- Duplicate numbering, or several series with no clear criteria telling them apart.
- Leaving out the IRPF withholding when it applies: many self-employed workers only think about VAT and forget that, when invoicing another professional or company, a withholding almost always has to be applied too.
- Using a simplified invoice (what used to be a “ticket” receipt) when the client actually needs a full invoice to deduct the expense.
When to apply an IRPF withholding
If you invoice professional services to another company or self-employed worker, as a general rule you must include an IRPF withholding on the invoice, at a reduced rate for the first years after registering as self-employed, if that applies to you. It’s one of the most common mistakes when starting out, because it isn’t intuitive that the withholding goes on your own income invoice.
A worked example of the final amount
You invoice €1,000 of professional services to a company. Here’s how what your client pays you is worked out:
| Item | Recently registered (7% withholding) | From the 3rd year on (15% withholding) |
|---|---|---|
| Taxable base | €1,000 | €1,000 |
| + VAT (21%) | +€210 | +€210 |
| − IRPF withholding | −€70 | −€150 |
| Total you collect | €1,140 | €1,060 |
You collect the VAT yourself and pay it on later via the 303 return. The IRPF withholding, on the other hand, you never collect: your client applies it and pays it straight to Hacienda on account of your income tax. Leaving it off the invoice doesn’t mean you “keep” that money — it’s a formal error that can end up triggering a request from the tax office.
When you work with us, we review the format of your invoices before it becomes a problem with Hacienda, not after.
Questions about a specific invoice?
Email us, no strings attached, at contacto@asesoriamadal.es and we’ll review it.
If you are thinking of registering, here is the complete guide to registering as self-employed: when, how and what it costs with us.