TFN includes a check digit for detecting erroneous numbers. The algorithm is based on simple modulo 11 arithmetic per many other digit checksum schemes. Example The validity of the example TFN '123456782' can be checked by the following process The sum of the numbers is 253 (1 + 8 + 9 + 28 + 25 + 48 + 42 + 72 + 20 = 253). 253 is a multiple of 11 (11 × 23 = 253). Therefore, the number is valid. See also Taxation in Australia National Insurance number (a similar number in the United Kingdom) Social insurance number (a similar number in Canada) Social Security number (a similar number in the United States) PPS number (a similar number in the Republic of Ireland) IRD number (a similar number in New Zealand) How to do TFN Field Validation in programs References Taxpayer identification numbers Taxation in Australia Identity documents of Australia