Your short-term capital gain is included in taxable income, so you're looking at $50,000 taxable income (less deductions and exemptions). That translates to a 25% tax bracket if you're single, 15% if you're married. Use the calculator at <a href="http://www.moneychimp.com/features/tax_brackets.htm" rel="nofollow" target="_blank">http://www.moneychimp.com/features/tax_brackets.htm</a> to get a ballpark idea of your tax. Roth IRA contribution is not deductible.