character in position 9. See the table for a sample calculation on the PPSN "1234567_A". The results are added together, and divided by 23. The remainder (modulus 23) indicate the check character position in the alphabet. In the example above, 121 divided by 23 leaves a remainder of 6, and "F" is the sixth character in the alphabet. The correct PPS number is therefore 1234567FA. Where the remainder is zero, the check letter is W. Check digit calculation in software The following are examples of software that provide checksum verification: PHP: The Pear class Validate_IE contains a checksum algorithm. Thesaurus Software Thesaurus Payroll Manager payroll software. Sage QuickPay payroll software. Expansion As the system allows for a maximum of ten million numbers to be issued, and with numbers having been issued to both the Irish and the legal immigrant population, expatriates, and many people who are now deceased, the current system will be in need of expansion in the not distant future. Since January 2013, the format uses a letter after the current check character. This has the advantage that all current PPS numbers remain valid. The letter after the check character would have a weighting of nine. The letter value would be assigned the same as the check character's. A=1, B=2 ... W=0. Examples of valid new PPSN 1234567TW 1234567FA Usage The number is currently used for a number of public services including education, health, housing, social welfare and tax however the net is widening raising concern about functionality creep. The number is underpinned in legislation by the Social Welfare Consolidation Act 2005 (Section 262) and a number of amendments, including data protection, have expanded its legal use as well as defining improper usage. The number has already been issued automatically to everyone born in the Republic of Ireland since January 1971 and those who commenced or were in employment since April 1979 – the primary trigger today for the numbers' issue is birth registration. A PPS number can be applied for at a PPS Number allocation centre. Applicants should show the reason for requiring a PPS Number, and provide Photographic ID and proof of address. See also NHI Number (a similar number in New Zealand) National Insurance number (a similar number in the United Kingdom) Social insurance number (a similar number in Canada) Tax file number (a similar number in Australia) Social Security number (a similar number in