Excess contributions are taxed at 6% per year as long as the excess amounts remain in the IRA. You can avoid the penalty on excess contribution by withdrawing the excess contribution plus earnings. Make sure that you tell the bank that you want to withdraw excess contributions.
From the IRS Publication 590-A: "For purposes of determining excess contributions, any contribution that is withdrawn on or before the due date (including extensions) for filing your tax return for the year is treated as an amount not contributed. This treatment only applies if any earnings on the contributions are also withdrawn. The earnings are considered earned and received in the year the excess contribution was made".
