Receiving a notification from the Agencia Tributaria (AEAT) is unsettling for any taxpayer or business owner. Yet an inspection does not automatically mean that a tax debt has been detected — it may be a routine cross-check, a review triggered by a statistical anomaly or a consequence of a third-party report. What matters is how you respond from the very first moment. The right preparation reduces both the final tax adjustment and the risk of penalties.
This guide explains the types of AEAT inspection procedures, what you must do in the critical first 48 hours, which documents you are required to keep and the most expensive mistakes to avoid.
Types of AEAT inspection procedure
Understanding which type of procedure you are facing determines your obligations and your strategy.
Comprobación limitada (limited review)
This is the most common first contact with the Tax Agency. It is conducted by the tax management office (Gestión Tributaria), not by tax inspectors. Key features:
- Only the documents specified in the notification can be requested
- The AEAT cannot conduct on-site visits to business premises
- The scope is limited to the specific tax and period mentioned in the request
- It typically relates to apparent discrepancies in your tax returns (e.g. income declared on Form 100 that does not match third-party data submitted by employers or payers)
Although limited in scope, a comprobación limitada can result in a settlement (liquidación provisional) requiring additional payment. If you disagree, you can file an administrative appeal (recurso de reposición) within one month.
Comprobación e investigación — full inspection (actuaciones inspectoras)
Full inspections are conducted by tax inspectors under Arts. 141–159 of the General Tax Act (LGT) and the Inspection Regulations (RD 1065/2007). They are significantly more powerful:
- Inspectors can visit business premises and examine all accounting books and records
- Multiple tax types and periods can be examined simultaneously
- Interviews can be conducted with company officers and employees
- Cross-checks with third parties (banks, suppliers, clients) are allowed
A full inspection concludes with an acta (assessment notice), which may be:
| Type of acta | Meaning | Effect |
|---|---|---|
| Acta de conformidad | Taxpayer agrees with the inspector’s findings | 30% reduction in penalty; cannot challenge the assessment later |
| Acta de disconformidad | Taxpayer disagrees | Maintains full appeal rights; no penalty reduction |
| Acta con acuerdo | Both parties agree in advance | 50% penalty reduction |
Never sign an acta de conformidad without first reviewing it in detail with your tax adviser. The financial saving from the penalty reduction is often smaller than the amount you would have saved by challenging incorrect findings.
Comprobación de valores
This procedure specifically challenges the declared value of assets — most commonly used in inheritance, gift tax or property transfer transactions where the AEAT considers the declared value too low. It does not follow the standard inspection rules and has its own appeal mechanisms.
The first 48 hours: what to do
The actions you take immediately after receiving an AEAT notification determine the trajectory of the entire procedure.
Step 1: Read the notification carefully
Identify: (a) the type of procedure; (b) the tax and period under review; (c) the specific documents requested; and (d) the deadline to respond. Note whether the notification was received through the DEHú electronic notification system (mandatory for companies and many professionals) or by post.
Step 2: Do not provide anything beyond what is requested
The notification will specify exactly which documents are required. Providing additional documents out of goodwill — summary spreadsheets, management accounts, internal memos — can open new lines of inquiry that the inspector had not originally planned to pursue. Provide only what is requested, in the form requested.
Step 3: Contact your tax adviser immediately
Do not make any verbal statements to AEAT staff before speaking to your adviser. In Spain, the inspector has the right to contact the taxpayer directly, but you always have the right to be represented by a tax adviser (asesor fiscal) or tax lawyer (abogado tributarista). Instruct your adviser to take over all communication with the AEAT from this point.
Step 4: Request a postponement if needed
If the deadline to provide documents is tight, request a postponement (prórroga) before the deadline expires. Submit the request through the same electronic channel (Sede Electrónica de la AEAT) where the notification was received. A brief, factual justification is sufficient.
Step 5: Gather and organise the requested documentation
Begin collecting the requested documents. For accounting records, ensure you have originals or certified copies of: purchase and sales invoices, bank statements, payroll records and annual accounts for the period under review.
Documents you are legally required to keep
Under Art. 66 LGT, the general prescription period for tax obligations is four years from the date the return was due. During this period, you are required to keep all documentation supporting your tax returns. For assets subject to amortisation (fixed assets, goodwill), the retention obligation extends until four years after the asset is fully amortised.
For companies and self-employed professionals, the core documentation includes:
- Official accounting books (libro diario, libro mayor) if you keep formal accounts
- Purchase and sales invoices (facturas emitidas y recibidas)
- Bank statements for all business accounts
- Payroll records (nóminas, TC2, IRPF withholding certificates)
- Annual accounts (balance sheet and profit-and-loss account)
- Minutes of general meetings and board meetings (for companies)
- Contracts supporting significant transactions
- Import/export documentation (customs declarations, DUA)
Note on electronic records: Since 2018, Spanish companies above certain thresholds are required to keep VAT books through the SII (Suministro Inmediato de Información) system. If your company uses SII, the AEAT already has real-time access to your VAT records — this both simplifies the inspection and means inspectors arrive better informed.
The most costly mistakes
Signing the acta de conformidad without advice
As noted above, signing the agreed assessment reduces the penalty by 30% but waives your right to challenge the inspector’s findings on the merits. If the inspector has made a legal error or applied an incorrect interpretation, signing the acta locks in that error. The saving from the penalty reduction is often far smaller than the potential recovery from a successful appeal.
Failing to submit allegations within the deadline
Before issuing the final assessment, the inspector must give you the opportunity to submit written allegations (artículo 157.3 LGT). This is your last opportunity to contest the inspector’s findings before the administrative phase. Missing this deadline — typically 15 business days — forfeits the ability to introduce new arguments at the administrative appeal stage.
Not requesting a stay of enforcement when filing an appeal
If you file an appeal (recurso de reposición or reclamación económico-administrativa) without simultaneously requesting a stay of enforcement (suspensión de ejecutividad), the AEAT will initiate collection of the full amount while your appeal is pending. If you ultimately win, recovery of the collected amount takes time. Always request the stay, attaching the required security (typically a bank guarantee).
Providing oral information without written confirmation
Everything you say verbally to an inspector can be recorded in a diligencia (an official document recording what was said). Always ensure that any significant verbal exchange is followed up with written confirmation from your side. Better still, conduct all communication in writing.
Making last-minute adjustments to accounting records
Any modification to accounting records after the inspection begins is extremely risky. Inspectors are experienced in detecting alterations — and discovering one transforms a tax case into a potential criminal matter (delito fiscal). If you identify a genuine error, declare it voluntarily and proactively with a supplementary return before the inspection reaches that period.
Practical example: how an inspection develops
Case: Tecnologías Aplicadas SA, a technology services company
In September 2025, Tecnologías Aplicadas receives a DEHú notification initiating a full inspection of Corporation Tax (IS) and VAT for fiscal years 2022 and 2023. The company had declared €1.8M in revenue and significant R&D deduction claims.
- Day 1–2: The company’s management notifies their BMC tax adviser. No additional documents are provided. A 10-business-day postponement is requested to compile the documentation.
- Week 2: The adviser reviews the IS and VAT returns, identifies a potential overstatement of R&D expenditure in 2022 and prepares a technical memorandum supporting the deduction methodology.
- Week 3–6: Documents are provided in the format requested. All communication is conducted in writing through the Sede Electrónica.
- Month 3: The inspector issues a preliminary findings notice (propuesta de liquidación). The R&D deduction is partially disallowed on technical grounds.
- Month 4: The company’s adviser files detailed allegations within the 15-day deadline, supported by technical reports from the company’s engineering team.
- Month 5: The inspector accepts part of the allegations. The final assessment is €45,000 — substantially less than the initial preliminary notice of €112,000. The company signs an acta de disconformidad and files a reclamación económico-administrativa to challenge the remaining amount.
The outcome — a 60% reduction in the initial preliminary figure — was achieved through preparation, timely documentation and strategic use of the allegations procedure.
How BMC can help
Our tax litigation and inspection defence team (tax-fiscal/tax-litigation) represents individuals and companies at every stage of AEAT procedures: from the initial notification through administrative appeals to the Tribunal Económico-Administrativo Central (TEAC) and, if necessary, judicial review. We also advise on preventive preparation — reviewing your tax position before an inspection begins so that there are no surprises.
If you have received an AEAT notification or inspection request, contact us for an immediate, no-cost initial review.
Legal references: Arts. 141–159 LGT (Ley 58/2003, de 17 de diciembre, General Tributaria); RD 1065/2007, de 27 de julio, Reglamento General de las actuaciones y procedimientos de gestión e inspección tributaria; Arts. 191–206 LGT (penalty regime).
