I reported on the 2017 return at the time of filing, that I did make contribution (as was my intention but I missed the April 15th deadline to make the contribution. TT tells one how much one can contribute at the time of filing but one has until tax deadline date to make the deposit). I am trying to find out if there is a way to contribute to the solo 401K for 2017 after the tax deadline. Filing an amendment to remove that contribution would be the other option, but I would like to be sure that the first option is not possible anymore.
