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 FileMaker Pro Custom Functions

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CheckIBAN ( IBAN )

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  Average rating: 4.1  (48 votes)
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Christoph Kaufmann, CLK

Checks whether the IBAN is correct or not

Sample Input:
CH65 0900 0000 3011 5642 8
Sample Output:

 Then copy & paste into FileMaker Advanced's Edit Custom Function window.


International Bank Account Numbers (IBAN) start with the country code and two figures, such as CH12. The function checks whether the these figures are correct or not. If not, the function returns 0. In that case, the IBAN is not correct and any attempt to make a payment with this IBAN will fail.

Note: these functions are not guaranteed or supported by Please contact the individual developer with any questions or problems.

This is my Custom Function and I want to edit it


5 most recent comments | Show all 10 comments

Changes on Jan 15, 2015:
- use local variables instead of script ($) variables
- Allow all characters except spaces since I need to check them all
- Filemaker ignores characters that are not numbers when calculating mod. Added a check for unallowed characters at the end.
- Experimented with DE-IBANS which "were too long with appended zeros", couldn't replicate any error. Please forward the IBAN in question.

Weakness: No checks for leading and trailing spaces, those may affect the IBAN. Use Trim or Supertrim in Auto-Enter.

Christoph Kaufmann, Zollikofen, Switzerland
January 15, 2015 6:53am

Works fine with my database.
Just a tiny bug: If you enter just the number "1" in the field the function returns also "1" for a correct IBAN. All other numbers and characters are recognized correctly as false.

Lutz Cleffmann, Düsseldorf, Germany
January 23, 2015 5:08am

Added check for a minimum of 6 characters. Thanks to Lutz Cleffmann.

Christoph Kaufmann, Zollikofen, Switzerland
January 23, 2015 11:51am

Chrystel wrote from Antibes:

> My company uses an old version of Filemaker is 5.5 pro FM.

This .fp5 solution uses a file and a script to check any IBAN:

Christoph Kaufmann, Zollikofen, Switzerland
January 23, 2015 12:00pm

z instead of p

IBAN = Filter ( IBAN ; "1234567890abcdefghijklmnopqrstuvwxy !!! p !!! ABCDEFGHIJKLMNOPQRSTUVWXYZ " ) // IBAN enthält keine Schweinereien; Leerschläge bleiben erlaubt.

Claudius von Wrochem, berlin
March 05, 2018 12:40pm

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