something isn't clear. we can't see your return. if your itemized deductions are at $17,300 before gambling losses and your gambling losses are $20K then your itemized deductions should be $37,300 afterward which exceeds the standard deduction. maybe, Turbotax is using the standard deduction because it already zero's out taxable income. another possibility is that you're counting your total amounts that can be used in itemizing but not taking into account the following limitations that would reduce the total to a deductible amount. medical is reduced by 7.5% of adjusted gross income, taxes are limited to $10,000, mortgage interest and contributions could be limited gambling losses go on line 16 of schedule A.
