BP (BP) says it's claiming a $9.9 billion tax credit on costs related to the oil spill cleanup operation in the Gulf of Mexico. The energy giant said Tuesday that the tax credit is related to the $32.2 billion charge it's incurring from the Gulf disaster, MarketWatch reported.

"We have followed the IRS regulations as they're currently written," outgoing CEO Tony Hayward said. The tax credit could effectively halve BP's contribution to the $20 billion escrow fund it set up to compensate victims of the spill at the behest of President Barack Obama.

Observers in the Gulf noted that the oil from the Macondo well appears to be vanishing from the surface of the water faster than expected. The Gulf is filled with oil-eating bacteria as a result of thousands of natural oil seeps, The New York Times reported. "Oil has a finite life span at the surface," John Amos, president of environmental advocacy group SkyTruth, told the Times. "At this point, that oil slick is really starting to dissipate pretty rapidly."