The cool thing is when your self employed you can write things off. I don't know if this would work for a Poker player, as I have never reported anything win wise on my taxes, because I have yet to have the pleasure of doing so. As a business person and being self employed you can write off so much of all of your personal bills such as your house payment, electric, water, ect... As you have a "home office"..... It is worth asking a tax professional if this is what you do for a living.
IANAA but being a former small business owner I can give a good starting point for some deductions should you have to report winnings.
1. Your computer is deductible for the % of time you use it for your business. So if you spend 75% of your computer time playing poker, you can deduct 75% of the expense.
2. Assuming you have a "poker area" say an office or desk, you can deduct the % of sqft that you are using as a percentage of your total rent and utilities. So if you have a 2,000 sqft house and your office is 100 sqft, you can deduct 5% of your rent and utilities. This is assuming your area is 100% used for poker.
3. Where most people will find help is in travel. ANY travel to play poker can be an expense. This includes travel to and from a local casino (and this year I think the write off is $.53 a mile) or long distance (say for a tourney). I believe even driving to your friends for a local game would be considered.
4. Another area that you can deduct is tools such as books, lessons, or any business get togethers. So if you take your poker friend Bob out for dinner with the intent of discussing your poker business, you can write that off.
Again I'm not an accountant so please research on your own, but these should be a good starting point. The write offs help offset the insane amount of taxes you will pay (15% off the top + whatever your federal taxes are). As a standard I would always take 35% of my earnings and hold them in an account I couldn't touch. I thought that was extremely aggressive and I still owed a few grand in taxes at the end of the year.