You can contribute to multiple Roth IRAs; however, your total combined contributions in any given tax year cannot exceed the amount of your annual earned income or the established annual contribution limit, whichever is less. The contribution limit is $5,500 for 2013 and 2014, and for those who are over the age 50, the contribution limit for both tax years is $6,500. Furthermore, your eligibility to fund a Roth IRA is determined based on your filing status and modified adjusted gross income for the tax year in which you wish to make the contribution. For example, in 2014 a married taxpayer under the age of 50 who files a joint income tax return with a spouse can make a full contribution ($5,500) if the modified adjusted gross income on the joint tax return is less than $181,000 and earned income is $5,500 or more.
If you cannot fund a Roth IRA because you earn too much, you may consider making after-tax contributions to a traditional IRA. The same annual contribution limits apply; however, eligibility to fund an after-tax IRA is not phased-out for those who earn higher incomes. IRS publication 590 provides all the information you need to determine your eligibility and the annual limits for IRA contributions. http://www.irs.gov/publications/p590/ch02.html#en_US_2012_publink1000253532