The Office of the Chief Financial Officer is announcing this evening that Standard & Poor's, one of three outfits that rate municipal debt, has given the District a "AAA" rating on a recent bond issue. That's S&P's top mark.

In a statement, CFO Natwar Gandhi calls it "a gilt-edged rating."

Now it's not quite accurate to say that the new rating represents a rise in the District's credit rating, since S&P is passing judgment on a new type of debt instrument, something called income-tax-secured revenue bonds only recently authorized by the D.C. Council. But according to City Administrator Dan Tangherlini, this bond issue is "practically the same as" and "will do the same work of" general-obligation bonds—whose ratings are most commonly cited when referring to the District's creditworthiness.

The District's GO bond rating has been rated by S&P at the medium-investment-grade "A+" since November 2005. Tangherlini declined to say whether he thought corresponding rises would be in order for ratings on GO bonds and other city debt. A look at the bond rating history for GO issuances shows that S&P has been historically the first agency to grant the District ratings hikes in the post-control board era, with other players Fitch and Moodys following close behind.

So what's it all mean?

Most importantly, it means that the District will pay less in interest and related debt-service costs when it needs to borrow cash from Wall Street. Which is good, considering the hundreds of millions the District needs to cut from the fiscal 2010 budget—Gandhi estimates $4 million in savings in 2010 alone.