John McManus Photo: Katherine Lambert

Less than 90. That's how many non-weekend, non-holiday days are left until the expiration of the federal first-time home buyer tax credit of up to $8,000 at midnight Dec. 1, 2009.

Home builders who live or die in the entry-level and/or first-time buyer market are counting the days. There are some hard deadlines coming fast.

In that time, how many new homes can be sold, built, and settled at the closing table? If a house doesn't begin going vertical in the next week or so, the likelihood that it will get any lift from the vaunted $787 billion stimulus bill's home buyer credit is slim.

Only 20-20 hindsight will allow proponents, detractors, economists, elected officials, and regular old voters to look at the tale of the tape of the home buyer tax credit programs—federal and state—and tell whether they worked, and if they worked, what they did to “stimulate” the broader economies they were intended to succor.

Part of why it's so hard to get a grip on the effect of the federal program is the fragmented nature of residential. But anecdotally, builders everywhere report that prices, interest rates, and this $8,000 credit add up to why they're on pace to start about 100,000 single-family homes in the next 90 days.

Take any one of those fairly significant tailwinds out of the equation, and the lives and livelihoods of the people and employers in the home building sector get that much harder. Witness the effect of the upward flutter of interest rates in early June. For most of the people willing and able to parry into today's home buying market, a $67 difference in monthly payments can make the deal either a go or a no-go, depending on whether it's $67 more or less.