Age only matters if you did not use the entire amount for medical expenses. If you took a distribution that was not used for medical expenses, answer based on your age at the time of that distribution so that TurboTax can calculate the 20% early-distribution penalty on that amount. If you took distributions not used for medical expenses both before and after reaching age 65, you'll need to split the Form 1099-SA into two, one for the portion distributed before age 65 on which the early-distribution penalty will be applied and another for the portion distributed after age 65 which is not subject to an early-distribution penalty.