I have been retired for a couple of years, and my husband just retired at the end of 2017. We have a son who is a college sophomore. We belatedly realized that in retirement our modified adjusted gross income will exceed the joint filers income limit for our I bonds interest exclusion, even though we are not expecting to take social security benefits until 2020. Thus far, we have earned about $15K in interest on I bonds that we originally purchased after 1989 for $34,000. Is there any advantage to cashing out all the I bonds now and adding the funds to our current 529 plan? Or should we just plan to use the I bonds for qualified educational expenses and pay taxes on the interest for the next couple of years when our tax bracket is at least lower than it will be after 2020?