Show the Five Sales

Every year the city tells each Philadelphia homeowner what it believes that home is worth, and that one number does more to set the family's tax bill than anything the family itself decides. The notice that carries the number, though, shows none of the sales the city used to reach it, so the homeowner is asked to trust a figure that the city will not show its work for.

The homeowner should be able to see the five sales that did the most to set that value. Those five sales belong on the notice itself and on the city web page for the home, each one with its address, the date it sold, and the price it brought, and each one close enough to the home, within half a mile, that the owner can drive past it and judge the comparison with his or her own eyes.

A homeowner who can see the five sales can do one of two useful things. Where the sales look like his or her home, the number earns the homeowner's trust, and the bill becomes something a family can plan around instead of something it resents. Where one of the sales plainly does not belong, the homeowner can point to that exact problem, and a conversation that usually goes nowhere becomes a conversation about a real house on a real street.

None of this asks the homeowner to become an expert, and that is the point. Today the person who understands how properties are valued, or who can pay someone who does, walks into the process with an advantage that has nothing to do with whether the city's number is right. Showing the five sales gives every homeowner the same starting place, on the same street, with the same facts the city had.

Cook County already does this. Each homeowner there receives a report showing the top five sales behind the value of the home, and the county treats that openness as part of the job rather than as a favor to the public. Philadelphia should also be open about the method it uses to value properties in general, because a method people can see is a method people can question, and a method people can question is one the city has to keep honest.

Cities run on trust that is earned in small, concrete ways, and few things the city sends a family each year carry more weight than the value it places on that family's home. Show the five sales, and the number stops being an order and becomes an answer the homeowner can check.