Rate Spread for Approved, Not Accepted

I have an application for a refinance dated 9/15/21.

LE dated 9/15/21
Preliminary CD issued 10/28/21 with closing date of 11/4/21. Only difference between LE and the prelim CD is the APR is different.

The customer sent an email on 11/2/21 that they were not going through with the refi.

What date do I use for the rate spread 9/15/21, 10/28/21 or 11/4/21?

The rate spread is determined by the rate set date. For instance, we use the rate lock date. I am not sure what your practices are on rate locks etc, so the date when you last set the interest rate on the loan would be the date to use.

Only difference between LE and the prelim CD is the APR is different.

Is the interest rate different? The APR could vary from the LE to the CD.

When was the interest rate last set? That would be the date used and based on what has been presented I would say 10/28/2021 is the date the final interest rate was set (absent a rate lock agreement).