Your first invoice as a self-employed (autónomo) must include a series of mandatory data required by the Invoicing Regulations. If any of them is missing, the invoice is not fiscally valid and your client will not be able to deduct the VAT (IVA). Here is exactly which fields you need and why.
The mandatory data on a full invoice
When you issue an invoice to another business or a professional, you must issue a full invoice. These are the fields that cannot be missing:
- Invoice number and series: each invoice requires a sequential number with no gaps within its series. You cannot jump from 5 to 7 or reuse numbers.
- Issue date: the day on which you issue the invoice.
- Transaction date: if different from the issue date, this must also be stated.
- Your details as the issuer: first name and surname(s) or company name, NIF, and registered address.
- Recipient’s details: name or company name, NIF, and address. Mandatory when the client is a business or professional.
- Description of goods or services: it must be sufficiently clear to identify the transaction.
- Taxable base: the amount before applying VAT (IVA).
- VAT rate applied: 21 %, 10 % or 4 % depending on the type of transaction.
- VAT amount: the amount in euros resulting from applying the rate to the taxable base.
- Invoice total: taxable base plus VAT amount (and minus the IRPF withholding, if applicable).
If you are in your first years as a self-employed, you must also include the IRPF withholding when invoicing businesses or professionals. The general rate is 15 %, but if it is the year in which you registered or one of the two following years, you may apply the reduced rate of 7 %, provided you have not carried out that activity in the previous four years.
Simplified invoice: when you can use it
The simplified invoice, commonly known as a receipt (tique), is designed for sales to the end consumer (private individuals) in low-value transactions, such as retail, hospitality, or similar services. You do not need to include the recipient’s details, although if the client requests them in order to deduct VAT, you must issue a full invoice.
On a simplified invoice the mandatory data are:
- Number and series.
- Issue date.
- Your details as the issuer: name, NIF, and address.
- Description of the transaction.
- VAT rate applied and, optionally, the expression «IVA incluido» (VAT included).
- Total consideration.
Numbering: the most common mistake for new self-employed
Numbering must be sequential and without gaps within each series. You may have several series (for example, one for domestic clients and another for foreign clients), but within each one there can be no gaps or repeated numbers.
Many new self-employed start numbering manually in Excel and end up with duplicate invoices or unintentional gaps in the numbering. This can cause problems during a tax inspection. Using software that manages numbering automatically eliminates this risk from day one.
Practical example with figures
Imagine you are a graphic designer, you registered in 2024, and you issue your first invoice in May 2025 to an advertising agency for a visual identity project.
| Item | Amount |
|---|---|
| Visual identity design (taxable base) | 1.000,00 € |
| VAT 21 % | 210,00 € |
| IRPF withholding 7 % (new self-employed, second year) | -70,00 € |
| Total payable | 1.140,00 € |
In this case you apply the 7 % withholding because you are in your second year of activity. The agency will pay you 1.140 € and will pay the 70 € withholding directly to the Spanish Tax Agency (AEAT) on your behalf. You will declare those 70 € as tax withheld at source in your annual IRPF return.
What about invoices to EU clients
If you provide services to a business in another European Union country, the transaction is outside the scope of Spanish VAT: the reverse charge mechanism applies and it is the client who declares VAT in their own country. On the invoice you must state your client’s NIF-IVA (verified in the VIES register) and add a note such as «Inversión del sujeto pasivo» or «VAT reverse charge».
If, on the other hand, you sell physical goods to another EU business, the transaction is exempt from VAT (intra-Community supply), and you must also state this expressly on the invoice.
If you have any doubts about how to account for a specific transaction involving another country, consult your tax adviser or the Agencia Tributaria.
Veri*Factu: what it is and when it will be mandatory
Veri*Factu is the AEAT system that requires each invoice to be recorded with a chained code and a tax QR code, and for the data to be submitted automatically to Hacienda. Its mandatory implementation is planned for 2028, although it is advisable to adapt beforehand to avoid last-minute pressure.
With Kullqi, every invoice you issue already complies with Veri*Factu from the very first moment: it carries its tax QR code, is chained to the previous one, and is sent automatically to the AEAT, without you having to configure anything at all.
Frequently asked questions
Can I issue paper invoices or do they have to be digital?
You can issue invoices on paper or in digital format. What matters is that they contain all the mandatory data and that you keep a copy for at least four years. If you use invoicing software approved for Veri*Factu, the record is guaranteed automatically.
Which VAT rate do I apply if I am unsure which one corresponds to my activity?
The standard rate is 21 %. The reduced rates of 10 % and 4 % apply to specific categories of goods and services set out in the VAT Act. If you are unsure which rate applies to your particular activity, consult your tax adviser or use the search tool on the AEAT electronic office.
Do I have to include the IRPF withholding on all my invoices?
Only when the recipient is a business or a professional required to withhold. If you invoice a private individual, you do not include a withholding. It also does not apply to invoices issued to clients in other EU countries or outside the EU. When in doubt about a specific case, consult your tax adviser.
What happens if I forget to include a mandatory piece of data?
An incomplete invoice has no fiscal validity: your client will not be able to deduct the input VAT and you may face a penalty in the event of a tax inspection. The solution is to issue a corrective invoice that rectifies the error. That is why it is important to use a tool that guides you from the very first field.
If you have just registered as self-employed and want to start invoicing correctly from day one, try Kullqi free for 14 days with no card required at app.kullqi.com.