Modulus checking
Validating account numbers
Modulus checking allows payment originators to confirm whether
the sorting code and account number given by customers are
compatible. Performing modulus checks promotes efficiency and
improves cashflow by reducing the risk of receiving returned
payments.
The Validating Account Number document describes
how modulus checking can be performed, either manually or by
computer programme. Modulus checks can be applied to validate
customers' account details before submitting an electronic payment
such as a Bacs Direct Debit or Bacs Direct Credit.
Validating account numbers (pdf file 326Kb valid from
23/04/12)
How to use Modulus Checking Files
The specification document provided on this page describes the
two general modulus checking methods available and gives specific
details of which to use for each sorting code. Inside the back
cover of the specification you will find details of how the
specification differs from the previous version. It also describes
the structure of the data files available for download below for
easy upload into modulus checking software.
Modulus weight table data
(txt file valid from 23/04/12)
Sorting code substitution
data (txt file 1Kb valid from 13/06/05)
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To ensure that you have the latest version of the specification
and the data files, download the latest versions (See Related
Information box opposite) and register
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specification and data files are available.
Note: Users of the information are reminded that VocaLink shall
accept no liability for any loss or damage that may be suffered as
a result of the incorrect processing of transactions resulting from
the use of the information contained in the above named files.