Preparing invoice data for UK and Spain e-invoicing rules

Why the data check comes before the system choice

Both the UK and Spain are moving to structured electronic invoices, and in both cases the rules describe what an invoice must contain and how it travels between businesses. Most businesses will not need to rebuild their invoicing setup first. They need to know whether the invoices they already issue carry the fields a structured format requires, and whether the customer and supplier records behind those fields are correct. That gap is usually found in the master data, not in the software.

The dates differ by market, so the first task is to map which invoices fall under which rule. The table below uses the official or regulator-linked dates available at the time of writing.

The UK position is still developing in detail. Secondary legislation may not complete its passage until autumn 2028 or early 2029, and HMRC has said it will publish updated VAT guidance before those regulations are final. A business planning for 2029 therefore needs to treat the data work as a standing task, not a one-time project.

What Spain's order adds

Spain's order sets the technical and functional elements of a public e-invoicing solution run by the Spanish tax agency, the AEAT. Private invoicing platforms must connect to that public solution, and the order also covers how invoices are sent, received and reported. The exact format, identification and transmission steps are in the official text and the AEAT's own pages. The worker does not choose a format. It checks your invoices against the field list your tax adviser or software provider confirms from those sources.

What is included

• A read-only inventory of the invoices you already issue, taken from the exports or files you provide
• A field check for each invoice, covering seller and buyer tax identifiers, addresses, and line-level VAT rate and amount
• An exception list of invoices that fail, grouped by the cause of the failure
• A fix list for customer and supplier master data, with a named owner for each correction
• A tracker that keeps each open fix on the list until someone closes it and the change is confirmed
• A short monthly summary for the finance or operations lead showing open and closed items

How the engagement runs

Audit

The audit confirms which markets, customer groups and invoice types are in scope. It also checks which systems hold invoice data and how the team exports it. The output is a short scope note that states which invoices are in scope for each date.

Process map

Next, the team and AiStaffo map how an invoice moves today, from creation to approval, sending and archiving. The map marks each point where a tax identifier or VAT detail can be missing, mistyped or stored in two places. Owners sign off the map before any build work begins.

Build

The build sets up the worker to read the agreed invoice exports and compare each record with the field list. It produces the exception list and the master data fix list. It does not write to your accounting or invoicing system. Any change to source data is made by a person in that system.

Run

Once running, the worker checks new invoices on the schedule you agree, adds new exceptions to the tracker, and reminds the named owner of each open fix. Your team decides whether to correct, reissue or leave a record as it is, and marks the item closed.

Support

Support covers changes to the field list when the official guidance is updated, new customer or supplier onboarding rules, and questions about the exception reports. Changes to the rules themselves are confirmed with the official text before the field list is changed.

Typical timeline

The table shows a planning shape rather than a fixed promise. The actual window depends on how many invoices you issue, how quickly exports can be provided, and how many master data records need review. The free audit sets the final plan.

What the client provides

The business provides read access or exports for the invoicing system, a sample of recent invoices in each format used, and the current customer and supplier lists. It also names one person for finance decisions and one for each area that owns master data, such as sales operations or procurement. Without named owners, the fix list stays open. The client also confirms the tax identifiers and VAT treatment that apply to each market, using its tax adviser or the official guidance.

What this does not cover

The service does not choose your invoicing platform, a clearance provider or a certified format. It does not give legal or tax advice, and it does not decide how a transaction is taxed. It does not submit invoices to HMRC or the AEAT, and it does not change records in your accounting system without a person approving the change. A field check confirms that required data is present and in the expected form. It does not prove that a provider's validation will accept every invoice.

Automation is also not the right tool in every case. A business that issues a few dozen invoices a month, with one customer list and one person handling both, may complete the check faster by hand. The worker adds value when invoice volume, the number of systems, or the number of master data owners makes manual checking slow to repeat.

This explains the rule in general terms; it is not legal or tax advice for your case.

Results depend on your own invoice data and volumes, which the free audit measures before any build begins.