To get a NIF, you need the following documents (in a Latin language or with a certified translation):
1. A photocopy of a valid passport.
2. Proof of residential address, with the name on the address matching the name on the passport. This can be:
(a) A valid driving license (both sides). For US citizens - issued within the last 12 months.
(b) First page of a bank statement, dated within the last 3 months.
(c) Utility bill from the last 3 months.
3. Power of attorney.