I don't see any way of setting this up in Quicken using the Quicken loan "wizard."
I guess the way I might approach setting this up would be to establish the loan as a zero interest rate loan, to schedule out the principal payments. Each time the interest rate changes I'd calculate the interest amounts due for the next 6 months using Excel and enter those amounts separately.
"Note receivable" … isn't that the same as what Quicken for Windows calls a "Lender Loan"?
How to create a Lender loan (Money I lend someone)
Please read https://help.quicken.com/pages/viewpage.action?pageId=3217587
@UKR
""Note receivable" … isn't that the same as what Quicken for Windows calls a "Lender Loan"?"
Yeah, I left that part out figuring the real problem was with the Quicken loan wizard not being able to handle a loan set up in this fashion.
@scott62556, when you say, in your original message that "the principal always remains the same" do you actually mean that the principal component of the payment is constant?
As worded, it suggests that the amount of money owed to you is constant … which would imply a balloon payment when the loan is due.