Have the monthly pmt widget show an accurate monthly tax pmt at the new offer price, not the old selling price. Often times homes that sold 20 years ago have a tax basis 5 to 10 X less than current market values. This means that the widget shows a tax payment which is incredibly low and inaccurate.
Example: A home is on the market for $1.3M yet the widget shows a monthly tax pmt of $91/mo, based on a 1995 selling price of $135k.
The correct estimated tax pmt should be ~1% of the $1.3M price, which is $1,083/mo.