Automatic Invoicing for Service Businesses in Spain

If you run a service business in Spain — a hairdresser, clinic, studio, or consulting practice — invoicing is an obligation you cannot avoid. But between the tax regulations, the different invoice types, and the need to issue them correctly, many professionals end up spending hours on administrative tasks that could be automated.

This article explains what the law requires, what types of invoices you need, and how to automate the process so it does not take time away from your core activity.

What the Law Requires in Spain

Obligation to Invoice

In Spain, every professional or business carrying out an economic activity is required to issue an invoice when the client requests one. In addition, in transactions with other professionals or businesses (B2B), an invoice is always mandatory.

For service businesses working with end consumers (B2C), you can issue simplified receipts for amounts below €400, but increasingly clients demand a full invoice — especially when submitting it to their employer or insurer.

Mandatory Fields on an Invoice

Under Spanish regulations, a complete invoice must include:

• Sequential number: Each invoice has a unique number within a series. Numbers must be consecutive, with no gaps. For example: F-2026-001, F-2026-002, F-2026-003.
• Issue date: The day the invoice is issued.
• Issuer details: Name or company name, NIF/CIF, registered address.
• Recipient details: Name or company name, NIF/CIF (mandatory in B2B; recommended in B2C if the client provides it), address.
• Service description: A detailed description of what is being invoiced. “Hairdressing service” is acceptable; “miscellaneous” is not.
• Taxable base: The amount before taxes.
• VAT type and amount: The applicable rate (generally 21% for services) and the resulting amount.
• Total: Taxable base + VAT.

Sequential Numbering: No Gaps

This is the point that causes the most problems when invoicing manually. If you issue invoice F-2026-015 and the next one is F-2026-017, the tax authority may ask what happened to F-2026-016. Gaps in numbering raise suspicions and can trigger an audit.

An automated system assigns sequential numbers automatically, eliminating this risk.

Invoice Series

You can (and sometimes must) maintain multiple invoice series. For example, one series for final invoices (F-2026-XXX) and another for credit notes (NC-2026-XXX). If you have multiple locations, you might use one series per location.

Types of Invoices You Need

Proforma Invoice

A proforma invoice is a quotation in invoice format. It has no tax validity (it is not reported to the tax authority), but it is useful for:

• Informing the client of the cost before they confirm the service.
• Sending a formal document to a company that needs internal approval before paying.
• Quoting long treatments or service packages.

A proforma invoice can be converted into a final invoice once the service is delivered and the client pays.

Final Invoice

This is the invoice with tax validity. The one you report to the tax authority, the one the client uses to reclaim VAT (if they are a business), or to submit to their insurer.

It must comply with all the legal requirements mentioned above: sequential number, complete issuer and recipient details, VAT breakdown.

Credit Note (Corrective Invoice)

When you need to fully or partially cancel an invoice that has already been issued, you cannot simply delete it — you issue a credit note that references the original invoice.

Common situations in service businesses:

• Full refund: The client cancels and you return their money. You issue a credit note for the full amount.
• Partial refund: The client paid for a 5-session package and only used 3. You return the difference and issue a partial credit note.
• Error in the original invoice: You made a mistake in the NIF, the amount, or the description. You issue a credit note for the incorrect invoice and a new corrected invoice.

Why Automate Invoicing

Time Savings

Issuing an invoice manually (opening the template, filling in the details, checking the sequential number, calculating VAT, saving the PDF, sending it by email) takes between 5 and 15 minutes. If you issue 100 invoices a month, that is between 8 and 25 hours per month spent invoicing.

An automated system generates the invoice in seconds, with all the correct data, and sends it to the client automatically.

Fewer Errors

The most common errors in manual invoicing are:

• A gap in the sequential numbering.
• Incorrect client NIF.
• Wrong VAT calculation.
• Invoice missing mandatory fields.

Each error can create problems with the tax authority or with the client. An automated system eliminates most of these errors because data is entered once and reused.

Everything in One Place

If your appointment system is one tool, your invoicing is another, and your payments go through yet another, you end up with three sources of information that do not align. Having invoicing integrated with appointment management and payments means everything flows automatically: the client books, pays, and the invoice is generated with the correct details.

How Invoicing Works in Marai

Initial Setup

Before issuing your first invoice, you configure your tax details once:

• Name or company name of your business.
• NIF/CIF.
• Registered address.
• VAT type you apply (standard 21%, reduced 10%, etc.).
• Invoice series (final invoices, credit notes, by location if applicable).
• Number format (prefix, year, numbering).

This configuration is stored securely and applied automatically to every invoice you generate.

Invoice Generation

When a service is completed and the payment is recorded, you can generate the invoice directly from the platform. Client details (name, NIF if provided, address) are filled in automatically from their profile in the CRM. The description reflects the service provided. The sequential number is assigned automatically with no gaps.

The Three Invoice Types

Marai supports all three types we have covered:

• Proforma: For formal quotes. No tax numbering.
• Final: Complete tax invoice with sequential numbering.
• Credit note: For full or partial cancellations, referencing the original invoice.

Integration with Payments

If the client has paid online (deposit or full payment through Stripe), the payment is already recorded in the system. The invoice automatically reflects the payment method, the amount, and the date. If the payment was made in cash, it is recorded manually and the invoice is generated in the same way.

Invoicing for Different Sectors

Hairdressers and Barbershops

Low-to-mid-priced services, high volume. Most invoices are B2C for small amounts. What matters is that the system generates invoices quickly when a client requests one.

Clinics and Practices

Mid-to-high-priced services, lower volume. Many clients need an invoice to submit to their insurer or employer. The client’s details (NIF, address) should be in the CRM so you do not have to ask for them each time.

Beauty Centers

A mix of one-off services and packages. Package invoices require a clear description (“10-session pressotherapy package”), and credit notes are common when the client does not use all their sessions.

What Does It Cost?

Invoicing in Marai is integrated into the platform. Online payments and invoicing are available from the Starter plan (€29/month). The Free plan (€0/month) includes appointment management, waiting list, and reviews, but not invoicing.

Plan	Cost	Invoicing
Free	€0/month	Not included
Starter	€29/month	Included
Pro	€59/month	Included
Business	€99/month	Included + multi-location

Conclusion

Invoicing in Spain has clear requirements you cannot ignore: sequential numbering, mandatory fields, VAT types. Doing it manually consumes time and generates errors. Doing it with a system that integrates appointments, payments, and invoicing turns it into an automatic process that requires almost no intervention.

Marai integrates invoicing directly into your business management. Configure your tax details once and let the system handle the rest. Get started for free and activate invoicing when you need it.