US Mortgage Application Payment Index Falls 1.6% in September

On Thursday, the Mortgage Bankers Association (MBA) reported that homebuyer affordability improved for the fourth consecutive month in September, with the national median payment applied for by purchase applicants decreasing to $2,067 from $2,100 in August, according to its Purchase Applications Payment Index (PAPI).

The PAPI measures how new monthly mortgage payments vary over time relative to income, using data from MBA’s Weekly Applications Survey. An increase in the index signals worsening borrower affordability as the mortgage payment-to-income ratio rises, while a decrease indicates improving conditions.

The national PAPI fell 1.6% to a reading of 155.0 in September, down from 157.5 in August. Preliminary estimates of median earnings—based on pre-shutdown August data—were up 3.2% year-over-year, while payments rose 1.3%. Stronger earnings growth pushed the PAPI down 1.9% from a year earlier, signaling improved affordability.

For borrowers applying for lower-payment mortgages (the 25th percentile), the national mortgage payment declined to $1,418 in September from $1,455 in August.

The Builders’ Purchase Application Payment Index (BPAPI) showed that the median mortgage payment for purchase mortgages from MBA’s Builder Application Survey decreased to $2,162 from $2,210.

Commenting on the report, MBA Associate Vice President of Housing Economics and Executive Director of the Research Institute for Housing America Edward Seiler said:

“Affordability improved for the fourth consecutive month, supported by lower mortgage rates and a growing housing supply. Affordability conditions have strengthened steadily throughout 2025, and with mortgage rates expected to stabilize and home prices remaining flat, we anticipate slightly stronger housing demand heading into 2026.”