For traditional IRAs, you are legally required to begin taking distributions in the year you reach age 70½. The dollar amount of the distribution is based on the value of the IRA account and age of the account holder. IRS Publication 590 provides details on how to calculate the minimum distribution. Required minimum distributions must start prior to April 1 of the year following the year in which you reach age 70½. Failure to take the required minimum distribution results in an IRS penalty tax of 50% of the amount that should have been distributed.