So the answer to your question is yes. You file a Joint federal return and include everything even if one person has no income. Was 3,000 the exact carry over amount? That seems odd. It might be more. 3,000 is the max loss you can show on your tax return and then you carry over the rest.
How much was his original loss? You get to first offset the loss against any gains you have each year so that can use more of it up. Then after applying the loss to the current gains you can take a max loss of 3,000 per year.
Did he use Turbo Tax for 2017? Even if he didn't he should have a Carryover worksheet in his paperwork and maybe a Capital Loss Carry Forward worksheet showing the amount transferring over to the next year.
