The first step to solve fee calculation issues is to reproduce the situation in a developement environment and describe what excactly shall be different. If it is an issue which occurs in a later transactions it is a good idea to prepare a contract with the problem at the current date to allow debugging without using GENDAT.
The debugging itself is to be done in the the Calculation of fees (ClcFecAmt and below) and usually requires relevant effort like the testing to the result, as at least the calculation rule changed needs to be carefully retested.
The standard of Date range handling of tables is to use half open intervals with the end date not in the period to be calculated. This is the standard handling in the (CBS-based) fee calculation as well. That means for the example calendar quarter that the periods are show as
etc. Many banks like it more to show the same thing as 01.01.-31.03. and 01.04-30.06. This can be adapted in IRTCAL.IrtGrdsAdjustForShow
Another common issue is, whether the first or last day is to be charged or not. In standard (according to the standard of Date range handling of tables ) the first day is charged, the last day not. Some banks are charging the last day as well or the first day instead of the last day. For CBS-Based this influences the booking of the liability amount (as in standard on the last day the amount is not longer in the balance. There are different places to be changed to solve those “offset by one” questions yet, but no standard solution at the moment (as the requirements differ in detail). To solve these issues it is very important to get the requirements from the customer as detailed as possible.
Please verify the condition used first. If the difference calculation is not used (with or without refund) it should be suggested. If the client does not accept the result, verify if a rule can be found. The examples should include some with minimum partly used.
If the calculation returns the wrong amount altough the number of days is correct please check the rate type used Maintaining Reference Interest Rate Types