IRR True Up's for Minimum Return Thresholds

An investor commits a dollar amount today to create a revolving line of credit for a borrower, receiving monthly variable cash flows in return.

At any given time, if the borrower wants to pay off the line of credit to release the lien, they must pay the investor a payoff amount to make the investor's return 6%.

Said another way - Based on the borrower's projected cash flow, I want to create a dynamic way to show them exactly how much they would need to pay at any given point in time to make the investor's return 6%.

The model I'm working on has 144 rows (144 months for 12 years).

Added 3 columns:

Cumulative Discounted Net Cash Flow: =XNPV($H$6,J$9:J9,G$9:G9)
Discount Factor: =1/(1+$H$6)^((G9-$G$9)/365)
Payoff: =-L9/M9

Select Payoff Date in cell I6
Payoff Amount: =-IFERROR(IF(G9=$I$6,L8/M9+H9,0),$H$9)

Leave Payoff Date cell empty, payoff amount for respective period is in column N.