How the Tax Code Works

Discover the calculation algorithm of the Italian Tax Code

Tax Code Structure

RSS
MRA
85
C
15
H501
S
RSS3 letters from surname (consonants + vowels)
MRA3 letters from name (1st, 3rd, 4th consonant if 4+, otherwise first 3)
852 digits of birth year
C1 letter of month (A=Jan, B=Feb, ... T=Dec)
152 digits of day (+40 for women)
H5014 characters of cadastral code
S1 control character (CIN)

Month Codes

JanuaryA
FebruaryB
MarchC
AprilD
MayE
JuneH
JulyL
AugustM
SeptemberP
OctoberR
NovemberS
DecemberT

Day Rule

👨 Males

Birth day from 01 to 31

15 → 15

👩 Females

Birth day + 40 (from 41 to 71)

15 → 55

What is Omocodia?

Omocodia occurs when two people have the same calculated Tax Code. The Revenue Agency resolves this by replacing some digits with letters.

Substitution table:

0→L1→M2→N3→P4→Q5→R6→S7→T8→U9→V

Control Character (CIN)

The last character is calculated with an algorithm that verifies the correctness of all previous characters. It is a letter from A to Z calculated using odd and even value tables.