How to disallow vat payable not paid before due date.

Dear Friends & Experts,

One new client is approaching me to conduct tax audit for 2012-13 . On verification of his books i found he has not followed various norms but his CA has allowed it . For eg:- Vat payable as on 31:3:2011 is not paid till 30 sept 2011 but allowed u/s 43b and same case in this year also ie Vat payable as on 31:03:2012(including that of opening of last year is also not paid till 30th sept 2012 but  his previous CA has not mentioned it in audit report and also allowed the same.

My query is that if it is paid in Oct 2012 what will be treatment  and what should be its treatment in previous years.

i also want to know whether 43b applies in case of VAT payable.

Thanks.