Need help with yearwise price calculation

Dear All,

Good Day. I am working at tuition Backoffice where I maintain list of all students and registrations and their fees. We offer little discount on fees after completion of every 12 months.

Let say student has enrolled in from 15th Aug - 22 and he keeps on taking classes. After completion of every 12 months, discount will apply for next 12 months. If student joins on a certain day in the month, we consider this as partial month and we only charge for no. of days of that month and we count 12 months from next month onwards unless he joins us from 1st Day of month. For example - If student joins on 10-Jan-2021 then we will count only 21 days and divide fee/21 and start counting 12 months from February month onwards. If he joins us on 01-Jan-2021 then counting starts from same month. This logic is also same at end. Student only has to pay for no. of days he has attended in last month and not whole month.


Now I am able to count formulas and calculate Year 1, Year 2 or Year 3 and so on and see what is total cost. however, I cannot do the same if I just want to see what actually he or she paid in 2021. Let says, student joins on 1st of July 2021 then I will consider Year 1 total fee till End of June 2022. However, if I want to see what was the fee paid year on year regardless of tuition anniversary and see the breakdown of 1-July-2021 till 31-Dec-2021 and 1-Jan-2022 till 30-Jun-2022 then I am not able to calculate how to detect those dates and calculate total cost year wise.

I have tried my level best to explain you the problem statement. Please see the attached image for you to understand it better. Apologies for any confusion I have created.

Please help me.