# Data center site due diligence: which documents prove what?

> Ask for documents, not descriptions. The **connection offer or access permit** proves capacity; the **land registry extract** proves ownership and charges; the **urban planning certificate** proves the use is allowed; the **option or purchase agreement** proves control. In Spain, also check the permit’s declared CNAE activity code.

By Razvan Toma, Founder & CEO, Ampervia · Last checked 2026-10-12 · https://ampervia.com/answers/data-center-site-due-diligence/

_What each document proves_

| Document | What it proves | What it does not prove |
|---|---|---|
| Published capacity at a node (e.g. CNMC map) | A request can be filed there | That capacity is reserved for this site |
| Access and connection permit / connection offer | Capacity reserved, works and date | That planning will be granted |
| Declared CNAE code on the permit (Spain) | The activity the permit can serve | Reuse for a different activity |
| Land registry extract | Owner, mortgages, easements | Contamination or buildability |
| Urban planning certificate | Permitted uses and parameters | Grid capacity |
| Option or purchase agreement | Control and price | That the seller can deliver vacant possession |
| Environmental / soil reports | Contamination status | Planning approval |

## Red flags

- “Near a substation” with no permit or offer.
- A permit held for a different activity (Spain: CNAE mismatch).
- Power-line easements across the buildable area.
- Capacity quoted in MW without saying grid or IT.

## Questions

### Who can confirm capacity?

Only the network operator, through its study and offer. Published capacity is indicative.

## Sources

1. [BOE — Real Decreto-ley 7/2026](https://www.boe.es/buscar/act.php?id=BOE-A-2026-6544)
2. [CNMC — access capacity map](https://www.cnmc.es/prensa/mapa-capacidad-transporte-20260213)

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