AMKA (Αριθμός Μητρώου Κοινωνικής Ασφάλισης — Social Insurance Registry Number) is the unique 11-digit personal identifier issued to every person insured under the Greek social security system. It is administered by EFKA (the Unified Social Security Fund) and is required for access to public healthcare, pension entitlements, and most government services in Greece. Foreign nationals living or working in Greece are also issued an AMKA.

How is the AMKA Luhn check digit calculated?

The check digit uses the standard ISO/IEC 7812 Luhn algorithm applied to all 11 digits. Starting from the rightmost digit and moving left, every second digit is doubled; if the doubled value exceeds 9, nine is subtracted. All resulting values are summed. The 11-digit AMKA is valid if and only if the total sum is divisible by 10.

What information is encoded in an AMKA?

The first six digits are the date of birth in DDMMYY format. The next four digits are a sequential serial number — the last digit of that serial (position 10 overall) encodes gender: an odd digit means male and an even digit means female. The eleventh digit is the Luhn check digit.

How does the AMKA encode gender?

The fourth digit of the four-digit serial block (position 10 of the 11-digit AMKA, immediately before the check digit) encodes gender by parity. An odd digit (1, 3, 5, 7, or 9) indicates the holder is male; an even digit (0, 2, 4, 6, or 8) indicates female. This is the same parity convention used by several other European social identity numbers such as the Danish CPR and the Finnish HETU.

Does a valid AMKA prove the person exists?

No. The validator only checks internal consistency — that the first six digits form a valid calendar date and that the final digit satisfies the Luhn algorithm. It does not contact EFKA or any Greek government database. A number can pass all mathematical checks while having never been issued.

Is the AMKA sensitive personal data?

Yes. The AMKA is personal data under Greek law and the EU General Data Protection Regulation (GDPR). Combined with a name it becomes directly identifying. Never log, store, or transmit AMKAs unnecessarily. This tool performs all validation locally in your browser — no digits are ever sent to a server.

Greece AMKA Validator

Greece AMKA validator

The AMKA (Αριθμός Μητρώου Κοινωνικής Ασφάλισης — Social Insurance Registry Number) is Greece’s 11-digit national social security identifier. Issued by EFKA (the Unified Social Security Fund), it is mandatory for accessing public healthcare, submitting tax returns, receiving pension benefits, and completing virtually every interaction with Greek public administration. Greek citizens receive an AMKA at birth; EU nationals and third-country residents working or residing in Greece are assigned one upon registration.

The number is compact but information-rich: it embeds the holder’s date of birth, a gender indicator, and a Luhn check digit that lets any software verify the number’s mathematical consistency without querying a remote server. This tool implements the full validation algorithm so you can instantly see whether an AMKA is internally valid and decode every embedded field.

How the format works

An AMKA is always exactly 11 decimal digits arranged as follows:

D D M M Y Y S S S G Q

DD — day of birth, zero-padded (01–31).
MM — month of birth, zero-padded (01–12).
YY — last two digits of the birth year.
SSSG — four-digit sequential serial number. The last digit G encodes gender: odd = male, even = female. Serial 0001 is the first person registered with that birth date.
Q — Luhn check digit (standard ISO/IEC 7812 algorithm).

Because only the last two digits of the birth year are stored, the validator infers the century heuristically: two-digit years 00–23 map to 2000–2023, and years 24–99 map to 1924–1999. This covers the entire practical range of living AMKA holders.

The Luhn check-digit algorithm

The Luhn algorithm was designed to detect common transcription errors such as single-digit mistakes and adjacent-digit transpositions.

Start from the rightmost digit (position 11) and work left.
Keep every digit in an odd position from the right (positions 1, 3, 5 …) unchanged.
Double every digit in an even position from the right (positions 2, 4, 6 …).
If any doubled value exceeds 9, subtract 9 (equivalently, sum its two decimal digits).
Sum all 11 resulting values.
The AMKA is valid if and only if the total is divisible by 10.

Worked example — an obviously fake AMKA

Consider the fictional number 15067501237:

Position	Digit	Action	Result
1	1	keep	1
2	5	×2 = 10, −9	1
3	0	keep	0
4	6	×2 = 12, −9	3
5	7	keep	7
6	5	×2 = 10, −9	1
7	0	keep	0
8	1	×2 = 2	2
9	2	keep	2
10	3	×2 = 6	6
11	7	keep	7
Sum			30

30 is divisible by 10, so the Luhn check passes.

Decoding the rest of the number:

Field	Value	Meaning
DD	15	Day 15
MM	06	June
YY	75	Year suffix 75 → inferred 1975
Serial (SSSG)	0123	Serial number; last digit 3 is odd → male
Check digit	7	Luhn-correct

This is a made-up number used only to illustrate the algorithm. Do not use it in any real system.

What the validator reports

Date of birth — the full year inferred from the two-digit YY field, with a flag if the date is not a real calendar date.
Gender — derived from the parity of the last digit of the serial block.
Expected vs. given check digit — shows exactly what the Luhn algorithm requires versus what was entered.
Luhn running total — the complete sum so you can verify each step.

All computation runs locally. No digits, partial inputs, or results are ever sent to a server.