The IRS limits the amount of your tax-deferred contribution each year. However, each person's maximum can be different and can change from year to year. You are responsible for making certain that all of your tax-favored retirement contributions do not exceed the IRS's limits.
Your failure to comply with the prescribed limits can result in taxes, penalties, and interest charges from the IRS. You should contact your 403(b) Plan carrier for assistance in determining your maximum contribution each year. You may stop or restart the amount of your contributions anytime during the year by signing a new Salary Reduction Agreement.