What a lawyer's invoice must contain: Article 6 of the Invoicing Regulation
Before mandatory e-invoicing arrives, a lawyer's invoice already has a minimum content set by the Invoicing Regulation. We review what its Article 6 requires, the deadline for issuing it and the duty to keep it.
The invoice is the document with which a lawyer gets paid, and also the one the Tax Agency uses to check their income and VAT. Its content is not free: it is set by the Regulation governing invoicing obligations, approved by Royal Decree 1619/2012 of 30 November. The consolidated BOE text is shown as updated to 31 March 2026, the publication date of the royal decree regulating mandatory e-invoicing.
The mandatory content: Article 6.1
| Letter | Content |
|---|---|
| a) | Number and, where applicable, series, with consecutive numbering within each series |
| b) | Date of issue |
| c) | Full name or company name of the lawyer and of the recipient |
| d) | Tax identification number of the lawyer issuing the invoice |
| e) | Address of the lawyer and of the recipient |
| f) | Description of the operations, with the data needed to determine the taxable base and its amount |
| g) | Tax rate or rates applied |
| h) | Tax amount charged, shown separately |
| i) | Date of the operations or of the advance payment, if different from the date of issue |
| j) | Reference to the exemption, if the operation is exempt |
The article also provides for other specific mentions, such as "invoicing by the recipient" or "reverse charge", for the cases where they apply.
Practical tips for a firm
Series and numbering. Numbering must be consecutive within each series. Using different series, for example for corrective invoices, helps keep order.
The description. Letter f) requires the data needed to determine the taxable base. For a lawyer, it is wise to identify the matter and the item, without revealing more client information than necessary. Professional secrecy also applies to what is written on an invoice.
Disbursements. Amounts advanced on the client's behalf have their own treatment, and should be recorded in the book of advances on account and disbursements, as we explain in the guide to the record books of the self-employed lawyer.
Withholding. When the client is a company or a professional, the invoice usually shows the income tax withholding the payer applies. We explain it in the guide to withholdings and form 130.
When it must be issued
Article 11 sets two rules:
- General rule: invoices must be issued at the time the operation is carried out.
- Business or professional clients: when the recipient acts as such, the invoice must be issued before the 16th day of the month following the one in which the tax became chargeable.
For a lawyer who works mostly for private individuals, the general rule is the one that applies: invoice at the time of the operation.
How long to keep it
Article 19.1 obliges professionals to keep invoices received and copies of those issued, among other documents, for the period provided in the General Tax Law.
What is coming: e-invoicing
The same regulation has been amended by Royal Decree 238/2026, which regulates mandatory e-invoicing between businesspeople and professionals. The minimum content will remain the basis, but the format and the way of delivery will change. We explain the timetable in the guide to mandatory e-invoicing.
Checklist
- Review the invoice template against the ten letters of Article 6.1.
- Check the consecutive numbering of each series.
- Describe the service without revealing unnecessary client information.
- Issue on time: at the time of the operation, or before the 16th of the following month if the client is a company or professional.
- Keep invoices issued and received for the legal period.
More guides in Solo and small-firm lawyers.
Fuentes
- Real Decreto 1619/2012, de 30 de noviembre, por el que se aprueba el Reglamento por el que se regulan las obligaciones de facturación (BOE-A-2012-14696, texto consolidado). Accessed 18 October 2026.
The specific data in this article come from the official sources cited.
