Hi Deepak,
this is the standard behaviour for fixed term deposits - the start of term is seen as included, the end of term as excluded by default.
So in order to have the last day (30.09.) included in the interest calculation, use 01.10. as end of term in the structure screen, which will (seen as exclusive) coincide with 30.09. inclusive.
Please note that for interest rate instruments, you have the choice if start or end date is included - but not for fixed term deposits.
Best regards,
Marie