BSN is the short form of Dutch Word – BurgerServiceNummer . In English, this is called  Citizen Service Number. This is a unique Personal Identification Number assigned by Netherlands Govt. This was introduced in 2007. To know more about this you can read this wiki page or you can refer the NL government website about it. This is a 9 digit number which should corresponds to 11-check or in dutch Elfproef

Example:

Check if 614961122 is a valid 11-check number
Total sum = 6 * 9 + 1*8 + 4*7 + 9 *6 + 6*5 + 1*4 + 1*3 + 2*2 + 2*1 = 187
Check if Total sum is divisible by 11 => 187 / 11 = 17 ( Remainder = 0)
This means 614961122 passes the 11-check standard.
What is Elfproef or 11-Check – Specific to BSN?
A variant of standard Elfproef is used for BSN. There is a small change in the standard. Weighted value for the last digit from Left to Right is changed from 1 to -1 . That’s all the deviation from the standard 11-Check.

Example:

Check if 614961122 is a valid 11-check number
Total sum = 6 * 9 + 1*8 + 4*7 + 9 *6 + 6*5 + 1*4 + 1*3 + 2*2 + 2*(-1) = 183
Check if Total sum is divisible by 11 => 183 / 11 = 17 ( Remainder = 7)
This means 614961122 is not a VALID BSN Number of Netherlands[/fusion_text][fusion_text][fusion_text]To do this validation easily in Excel, I created a Excel VBA function using above Algorithm, to validate if a given number is a valid BSN number of Netherlands or not.
Note: With validity, I do not mean, if this is a real existing BSN number or not, but whether that number qualifies the Elfproef or 11-check. VBA Code to do 11-Check (Elfproef) for BSN

Function IsValidBSN(bsn As String) As Boolean

'first check if it has 9 digit
If VBA.Len(bsn) = 9 Then
Dim totalSum
totalSum = 0

' Follow standard 11-check algorithm till the
' second last digit of the 9 digit number
For i = 9 To 2 Step -1
totalSum = totalSum + CInt(VBA.Mid(bsn, 10 - i, 1)) * i
Next

' Weighted multiplication factor for
' the last digit is (-1)
totalSum = totalSum + (CInt(VBA.Mid(bsn, 10 - i, 1))) * (-1)

'11-Check true if divisible by 11
If (totalSum Mod 11) = 0 Then IsValidBSN = True Else IsValidBSN = False

Else
IsValidBSN = False ' Not a valid BSN, if length is <> 9 Digits
End If
End Function

What is the use of this function ?

This is the most important question about any thing you do… What would you do with this? What is the use of it? So this function can be used for checking if entered BSN number is a valid BSN number or not. There are companies or organizations which uses excel as a Data form for the users to enter their details like Name, Date of Birth, Address, BSN etc. In such form, you can implement such validation to prevent from entering an Invalid BSN number.

How to use this function ?

This code can be used in many different ways, depending on your requirement. You can call this function on clicking on a button to validate the entered BSN number and display the result accordingly.

Another way of using this function can be — using it as a UDF (User Defined Function) or custom function. Where you can use it like a formula to check the validity of the BSN number entered by a user in a cell.