Tracking irregular loan payments (Land Contract)

[Scott VandenBerg]

Hello,  I sold a property on Land Contract about a year ago.  We fully amortized the purchase price over 5 years with interest.  We also added a separate escrow amount for property taxes.  Buyer has been making very irregular payments (irregular in the frequency and amount).  Buyer is currently behind with payments.  I would like to produce an accurate loan statement so that we can both see where things are at.  Can anyone point me to a spreadsheet that allows for multiple irregular payment dates, and applies the correct amount to P&I.  Also, I am unsure how to handle the escrow payment as the payments are never allocated to P/I vs. Escrow.  Thank you