FYI, I just updated USA Mega with all the Oklahoma Powerball information, since Oklahoma just joined the fun yesterday (first Powerball drawing tomorrow).
I'm not sure if she'll see this, but I just wanted to thank Mary at the Oklahoma Lottery for her help.
Mary is one of the nicest people I have ever dealt with at any state lottery, and I know a lot of nice people at various lotteries. I hope the Oklahoma Lottery knows what a gem they have!
Surprisingly, in all my research on the web, I could not locate a single source that said what the Oklahoma tax withholding rate is on lottery prizes, but Mary had the info in her files. Now USA Mega seems to be the only place with that info. (Check out the Jackpot Analysis page for the tax rates.)