In 2015, you can contribute up to $5,500 of taxable compensation to a Traditional IRA, or $6,500 if you’re age 50+. If you participate in a retirement plan through work,
tax deductibility of your IRA contribution will phase out with modified adjusted gross income (MAGI) between $61,000-$71,000 if you're single, or $98,000-$118,000 if you're married filing jointly.
If your income is too high for a deductible contribution, then eligibility to contribute to a Roth IRA in 2015 phases out between $116,000-$131,000 if you're single, or $183,000-$193,000 if you're married filing jointly.
And if your income is still too high (oh darn!), then you can circle back and make a non-deductible contribution to a Traditional IRA, and then use the so-called "back door" strategy to convert it to a Roth IRA. But if you go down that path, be sure the transaction is handled properly (including time lapse for "step transaction doctrine") and that you’re familiar with IRS Form 8606 reporting requirements.