As of 2015, taxpayers under 50 years old may make a maximum of $5,500 in total Individual Retirement Account contributions without incurring an overcontribution penalty, while taxpayers 50 and older may contribute up to $6,500, the Internal Revenue Service reports. Contributions that exceed those limits are taxed at 6 percent.
Contribution limits define the total a taxpayer may invest in all IRAs, including traditional and Roth accounts, according to the IRS. Income and filing status may affect the amount the taxpayer may invest in a Roth IRA. To avoid the 6 percent tax penalty on excess contributions, the taxpayer can withdraw the excess amount along with any earnings it accrued before his tax filing deadline date.