Request tax ID
Requesting another person's tax ID under a power of attorney
With a power of attorney you can request the tax identification number for another person — for a parent or a relative, for instance.
What has to be enclosed is the power of attorney and a copy of an identity document. That copy is the one belonging to the person who granted you the power of attorney, not your own.
This confusion is the most common reason why such a request comes back — and then a copy of an identity document has been in the post that nobody needed.
What the power of attorney has to say
It must show that the other person entitles you to act before public authorities, and it must be signed. There is no special form for it; the original and a copy are both possible.
The reply does not come to you
Even with a power of attorney, the information goes to the registered address of the person whose number is concerned. Anyone who wants the number in their own hands has to be given it from there.
If the person cannot grant you a power of attorney
If someone can no longer grant a power of attorney for health reasons, this route does not help. The route then runs through court-ordered legal representation — and there is a separate page for that.
What that costs
The price is fixed. A request always concerns exactly one person, and the letter is always one sheet — there is nothing the extent could depend on. The sample calculations are on the page about Request tax ID.