The oath turns the file into a court act
A translation on its own is just typing. It becomes an official item when the translator swears to it in front of a clerk at the court, in the step called the asseverazione. That oath is what a foreign reader relies on. The oath is taken at the court, so the sworn file counts as a court act. To apostille a Certified Translation Affidavit in Italy you therefore go to the Procura della Repubblica, not to the Prefettura.
Who may swear the translation
The person who swears is the translator, not you, and not the office that wrote the original paper. Courts differ on whom they will hear, and some keep a roll of translators they recognise. So the first question when working out how to apostille a Certified Translation Affidavit is whether your translator can be heard at the court you plan to use. Ask that court before you commission the work, because a rejected translator means starting again.
The order of the steps
Order costs money here more than anywhere else on this site. Ask the reader abroad whether it wants the original paper stamped as well, and whether it wants the stamp on the original translated too. Only then commission the translation, take the oath, and lodge the sworn file. When you apostille a Certified Translation Affidavit in Bologna out of sequence, the usual result is a second oath and a second stamp for the same words.
The language question is not ours to answer
Nothing on this page fixes which language your file must be in. That is decided by the office that will read it, so put the question to that office in writing and keep the reply. Ask two things while you are there: which language, and whether the sworn version must arrive with the stamp attached. Guessing is expensive because a sworn translation cannot be edited after the oath; it has to be done again.
Paying for the stamp
The apostille cost for a Certified Translation Affidavit in Bologna rests on a €16 tax stamp for the document. You buy it, fix it to the sworn file, and lodge the two together. Certain papers are let off the charge, so raise it at the desk first. Court dues for hearing the oath and the translator's own fee are separate matters, set by the court and the translator, and they sit outside the figure quoted here.
Keeping the bundle bound
The sworn file is a single object: the original, the translated pages, the oath sheet and the stamp. Once bound at the court, it must stay bound, because the binding is what ties the oath to the words. The legalisation of a Certified Translation Affidavit in Bologna is undone the moment somebody removes a staple to run a photocopy. Scan the whole bundle before it travels, then post it without opening the fastening.