but be careful, a NIE number is only valid for 3 months, if you have these, but not for the above tasks.
That is, if one uses the NIE number 3 months for tax purposes, it extinguishes tacitly and you must, if you want to use them later after 3 months, apply again.
So it makes sense, the one NIE number requested only if you need them in a timely manner.
In the meantime, the NIE number is also requested for other purposes.
Since some banks, or insurance companies, telephone companies, ect ... request a tax number from the applicants,
many use the NIE number.
When requesting a Residencia keep the same number, since the then provisional NIE (the tax number) also later in a Residencia the same tax number remains