Hello

I have built a quite extensive loan calculator, for both Annuitet and even repayments, and the calculator is working fine.
The formulas for it are a bit complex (perhaps I wrote them a bit too complicated )

Anyway, I want to be able to pay into the principal amount at any given time in the model, but I have no idea how to adjust the formulas to replicate that?
Can anyone assist?

I have attached the document for further verification.

MAny Thanks!
Loan Calculator.xlsxLoan Calculator.xlsx