Italian Tax Code
Plain English
It's a 16-character code that identifies you for almost everything official in Italy. Think Social Security Number in the US or National Insurance Number in the UK. The letters and numbers are generated from your name, date of birth, gender, and place of birth, so yours is unique to you.
Why it matters
You can't open a bank account, sign a phone contract, register with the health service, get hired, or rent a place without one. Even buying a SIM card needs it. It's usually the very first thing new arrivals sort out.
Real example
"On her second day in Bologna, Ana walked into the Agenzia delle Entrate with her passport and visa. She filled in a one-page form and walked out 20 minutes later with her codice fiscale on a paper slip."
Common confusion
People think they need a residence permit first. You don't. Walk in with just your passport and you'll get one. You can also request it from an Italian consulate before you even fly over.
Official source
Agenzia delle Entrate