Mismatch in capitalized interest flows in SAP with that with Banks

Dear Friends,

We are implementing treasury at one of out client. The product is 51A.

The interest calculation done by banks is not matching with the flows that are generated in SAP for capitalized interest.

I had never encountered such issue with my previous project. flows always used to match with that in banks. But here, banks are following different methods I guess.

Eg:-

FD start date: 13.03.2014

FD end date : 13.03.2015

Now as of 31st march, the banks are calculating the interest for 18 days as follows:-

(P * R * 18) / (31*12*100)       - { Denominator comes to 3720 }

and in SAP, we are calculating as

(P * R * 18) / (365*100)         - { Denominator comes to 36500 }

What to do in such cases where the interests are not matching.

Since the initial 18 days interest itself is not matching, none of the further capitalized interests are matching.

Please suggest what can be done.

Regards,

Rohan