In the case of single persons covered by other employer retirement plans, deductibility of IRA contributions is limited by their adjusted gross income. The amount you can deduct is phased out as your AGI climbs above $56,000 for 2010 (up from $55,000 for 2009). At $66,000 ($65,000 for 2009), deductibility drops to $0.

For a married individual filing separately and where either spouse participates in an employer-sponsored retirement plan, the phase-out begins at $0. So, at $10,000 of income, no deduction is permitted for an IRA contribution.

IRS Publication 590 provides worksheets to help you with your calculations.