Rookie question - loan mod

[Jeremy K.]

Just doing my research and wrapping my head around NPLs.  I have a question about the timing of the modification:

Example: my borrower has 10k in arrears, and an interest rate of 12%

Let's say I call him up and we agree on him paying 5k in arrears, I forgive the other 5k and I lower his rate to 10%.  Who goes first?  Does he pay me the $5,000, and then I modify the loan after I receive payment?  What protection does the borrower have that we made the deal and all they have to pay is 5k and I'll forgive the other 5?  I guess I'm unsure how that process works.