You don’t need particular forms. You just need pen and paper.
Following this, there are – as examples – two types of auto-certification: the first one is about an auto-certification concerning the residence while the second one reproduces the auto-certification about family status.
The signature doesn’t need authentication neither has to be undersigned obligatorily in front of the employee to which it is presented.
The auto-certification in always exempt from every fees or stamp tax.