Interest due but not paid

Hello,

We have FX loans on which usually interest due is not paid during the same month.The payment is made in next month. What client requires is  that when it is due it should generate appropriate accounting document (deb interest and crediting liability) and in the month it is paid-it should debit the liability and generate exchange variation entries.These scenario should not impact the case whereby I am paying interest due in same month.

Hence my query is:

1.How to generate this type of entries and impact exchange variation

2.How the entries where there is no delay in payment - be differentiated from above entries

Help wud be appreciated.

Regards