Omocodia: When Two People End Up With the Same Italian Tax Code

Omocodia is the collision of two fiscal codes: it happens when two different people generate the same theoretical 16-character sequence from their personal data. With 60 million Italians, it is bound to happen.

How the tax office fixes it

The Agenzia delle Entrate takes the duplicated code and replaces some digits with letters, starting from the rightmost numeric positions: 0-L, 1-M, 2-N, 3-P, 4-Q, 5-R, 6-S, 7-T, 8-U, 9-V.

What to do

Nothing: the code with substituted letters is your official, fully valid fiscal code. Do not "correct" it back to the calculated version — it is a normal administrative procedure, not an error.

Why calculators cannot predict it

No online calculator can know whether your sequence was already assigned to someone else: it depends on registration order.

Read the complete guide to omocodia and use the free calculator to double-check your data.