Under what circumstances would one need a NON residency certificate? This form is available, I think, by applying using Extranjeros form number EX13.

It would probably be necessary to ensure non-residency status of a bank account and so avoid the risk of the account being frozen.

You may need it if you left Spain to prove you are no longer resident in Spain.

I don`t think it is anything to do with non res bank account, cos if you are here for more than 3 months you shouldn`t have one anyway. ;-))

You are confusing the requirement to sign on the register of foreigners after 90 days with tax residency.

Being on the register does not necessarily make you resident from a fiscal point of view.

The reason you need a non residents certificate is that if you have an interest bearing account as a non resident, the interest is paid gross. If your are tax resident then 18% will be deducted at source by the bank. If you don't want this deduction you have to prove your are not (tax) resident and thus entitled to hold a non resident account..

When we had a non res account, the bank used to send a form to fill out saying that we were still non res.

I know there were some problems earlier this year where banks were sending out the forms and they were not being received (old address etc) and the accounts were frozen when they got no response.