TT/Maryland (well, any TT state that has estimated tax voucher(s)) will prepare those for you when you have an excessive amount of MD tax due from lack of enough tax withholding. You don't have to pay them if you don't want to - and you can go into TT/MD and turn them off - but you may end up with an underpayment of estimated tax penalty on your 2016 MD return. TT/MD prepared them to avoid that possible penalty.
