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.