IRS.gov; Publication 535; 2010 15 percent complicated taxes IRS Publication 535 (211) depletion http://www.irs.gov/publications/p535/ch09.html http://www.irs.gov/publications/p535/ch09.html complicated taxes depletion allowance for a timber sale Publication 535 (2009), Business Expenses http://www.irs.gov/publications/p535/ch09.html complicated taxes Internal Revenue Service: Depletion complicated taxes IRS deduction off Gross Revenues deduction off Gross Revenues mineral depletion allowance oil depletion credits depletion allowance