The number opens the first door and no more. A calm look at the registrations, the records and the island-specific details that come next.
There is a persistent belief that the NIE is what makes you self-employed in Spain. It is not. The number identifies you to the administration, and everything that follows — being allowed to invoice, being counted as a contributor, being visible to the tax authority as a working business — comes from separate registrations that you have to make deliberately.
The tax side is the first of them. Registering an activity means declaring it, choosing the classification that describes what you actually do, and stating when you intend to begin. The classification is not a formality: it shapes what you declare afterwards and how your invoices are treated. Getting it right at the start is considerably cheaper than amending it once a year of filings has been built on top of a wrong choice.
Then there is the contributions side, which is a different authority with a different registration and its own conditions. The two need to agree with each other, particularly on dates, and the rules governing order and timing are set nationally and revised from time to time. Confirm the current position through the official channel or an asesor rather than assuming last year's sequence still applies.
The island detail that surprises newcomers most is indirect tax. the Canary Islands do not operate the same consumption tax as the mainland; the Canaries have their own system, with its own rates, thresholds and filing habits. That affects how you invoice a client in Arrecife, a client in Madrid and a client in Berlin quite differently. It is genuinely worth a paid hour with a local adviser before you send invoice number one, because it is the kind of thing that is awkward to unwind retrospectively.
Records are the unglamorous core of the whole business. Sequential invoice numbering with no gaps, expenses kept with their receipts rather than reconstructed in a panic, a separate account so personal and business movements never have to be untangled, and quarterly obligations diarised rather than remembered. Most people who find self-employment here miserable are not struggling with the rules; they are struggling with three months of unfiled paperwork.
You will also want online access to the administrations, which in practice means a digital credential tied to your identity. The data behind it has to match what the registers hold — same name, same order, same number — and a mismatch is a slow, dull problem to fix. Sort the credential early, back it up, and note when it expires.
None of this is a reason to be discouraged. Plenty of people run good, small businesses from Lanzarote, working with clients across the islands and beyond. The point is simply to be honest about what the number does and does not do: it identifies you, and that is all. The registrations, the classifications, the contributions and the filings are the actual work, and where circumstances are anything but standard, a qualified adviser earns their fee several times over.