It was something everyone could agree on: a user-friendly Web site showing how much money the government spends – a very literal display of “your tax dollars at work.” The Office of Management and Budget (OMB) even partnered with one of its banes, the nonprofit watchdog OMB Watch, to devise the software. But something appears to be clouding all this much-trumpeted transparency: The numbers don’t add up.

The new site, known as USASpending.gov, was unveiled ahead of schedule last December, and its basic design is true to its mandate. Its welcome screen boasts: “Where Americans Can See Where Their Money Goes.”

Well, not really. I tried to use the site to see how the surge in Iraq had affected the Pentagon’s contract spending. Summary reports from the Federal Procurement Data System (FPDS), the official source for all contracting numbers on the site, showed exponential growth in Department of Defense spending on contracts from 2000 to 2005. So when I logged on to USASpending.gov in early March, I expected to see a continued upward trend. But my first visit yielded something less than transparent: The site was already displaying total contracting figures for 2006 and 2007, citing FPDS as its source. That would have been about two months ahead of schedule, as the official numbers for 2006 were only scheduled for public release last Friday. The site gave no indication, however, that the agency numbers weren’t final and definitive.

I then pulled up the total Pentagon contracting figures for 2007, which revealed a downward trend from 2006. How could it be that we actually spent less on defense contracts in 2007, the year of the surge, than we did in 2006? I thought all the results might not be in yet, but only the 2008 numbers had an asterisk, implying that the other years were complete.

I checked back last month, and the chart made more sense, showing an upward trend. So why were the numbers a moving target? I started calling around and learned two surprising things. First, all appearances to the contrary, the site’s summary numbers for both 2006 and 2007 are still changing over time as more reports flow in – though nothing indicates when a year has been officially closed out. Second, and more disturbing, the numbers on OMB’s site depart from other established sources because OMB is “cleansing” the agency data. But nothing on USASpending.gov says just how the data are being cleansed.

There is nothing wrong with data cleansing in principle; the more accurate the numbers, the better. But users of USASpending.gov deserve to be told why and how data are being cleansed for the site to truly provide accountability. Illusory transparency is harder to see through than no transparency at all.