Generator · Greek data

Greek AFM

Endpoint GET /v1/gr/afm

What it covers

Returns a valid Greek AFM (tax registration number, used by both persons and companies) with a correct check digit. Use `format=vat` for the EL-prefixed VAT number. Set `invalid=true` for an AFM with a deliberately wrong check digit.

How it’s calculated

The Greek AFM's 9th digit is a weighted mod-11 check digit over the first eight digits, using powers-of-two weights 256..2, taken as the plain remainder and reduced mod 10 so it is always a single digit 0-9.

Algorithm

Take the eight payload digits d1..d8 (the AFM is nine digits; the ninth is the check digit being computed). Read them left to right as integers 0-9.
Assign position weights, most significant digit first: w = [256, 128, 64, 32, 16, 8, 4, 2] (i.e. 2^8 down to 2^1). d1 pairs with 256, d2 with 128, ..., d8 with 2.
Compute the weighted sum S = 256*d1 + 128*d2 + 64*d3 + 32*d4 + 16*d5 + 8*d6 + 4*d7 + 2*d8.
Take the remainder modulo 11: base = S mod 11 (a value 0-10).
Because AFM uses the 'remainder' style, the raw check value is raw = base (no 11-complement is applied).
Apply the 'mod10' overflow rule: checkDigit = raw mod 10. This maps the single awkward residue 10 to 0, so the result is always a single digit 0-9; no residue is ever rejected.
Append checkDigit as the ninth digit to form the full 9-digit AFM: d1 d2 d3 d4 d5 d6 d7 d8 checkDigit.

Worked example

AFM payload 12345678? (compute the 9th/check digit)

Payload digits: d1..d8 = 1,2,3,4,5,6,7,8.
Weights: 256,128,64,32,16,8,4,2.
Products: 256*1=256; 128*2=256; 64*3=192; 32*4=128; 16*5=80; 8*6=48; 4*7=28; 2*8=16.
Weighted sum S = 256+256+192+128+80+48+28+16 = 1004.
base = 1004 mod 11: 11*91 = 1001, so 1004 - 1001 = 3, base = 3.
remainder style: raw = base = 3.
mod10 overflow: checkDigit = 3 mod 10 = 3.
Ninth digit = 3.

The check digit is 3, giving the full AFM 123456783.

References

AFM (Αριθμός Φορολογικού Μητρώου) — Independent Authority for Public Revenue (AADE), Greece

Edge cases

Leading-zero AFM: the first payload digit can be 0, producing a valid 9-digit AFM that drops below nine digits if parsed as a number (the edge generator emits this deliberately).
Zero check digit: residue 0 (or the residue 10, which the mod-10 overflow rule folds down to 0) yields a ninth digit of 0 — a fully valid AFM.
Repeated-pattern payload: all eight payload digits equal (e.g. 88888888) still produces a valid check digit; it is a valid corner, not a rejected input.

Gotchas

Weights are powers of two 256,128,64,32,16,8,4,2 applied most-significant digit first — not a 1..9 or 3-1-7 sequence. Aligning them from the wrong end gives a wrong check digit.
The check value is the plain remainder (S mod 11), NOT the 11-complement used by many other European mod-11 schemes (CVR, NIF, IČO). Do not compute 11 - (S mod 11).
The overflow rule is mod10: a residue of 10 becomes 0 rather than marking the number invalid, so every eight-digit payload has exactly one valid AFM and none are 'unissued'.
The VAT form prefixes the AFM with EL (not GR); the check-digit math is identical and operates only on the nine digits.

Parameters

Parameter	Type	Description
count	integer1–1000	Number of records to return, 1–1000 (your plan may lower this). Omitted returns a single record; set it for a batch.
edge	boolean	Restrict output to valid edge-case AFMs from the rare corners.
extreme	boolean	Return a correct value wrapped in a hostile encoding (untrimmed whitespace, invisible/zero-width characters, BOM, or bidi/combining marks). Homoglyphs are excluded so the value stays machine-parseable; it still validates after normalisation.
format	"national" \| "vat"	Rendering: bare 9-digit AFM (default), or the EL-prefixed VAT number.
invalid	boolean	Return an AFM with a deliberately wrong check digit.
seed	integer	Integer seed for reproducible output: the same seed always yields the same record.

Response fields

Field	Type	Description
value	string	The identifier in the requested format (national or VAT).
digits	string	The canonical, unprefixed 9-digit AFM.

Other generators for Greece

Greek AMKA Greek company Greek company name Greek email address Greek IBAN Greek person Greek person name Greek product or service offering Greek vehicle registration plate

See all generators for Greece →

The same kind of identifier elsewhere

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