Can a married couple file separately with on filing a short form and the other filing a long form?
1. There is only one form this year. 2. If the married couple files separately, both will use a 1040. 3. As another poster indicated, if one spouse itemized, both do, even if that means $0 on one schedule A.
If by "long form", you mean itemizing - no. If one spouse itemizes, then the other one also must do so.
There is only one form now. If you are thinking of one spouse itemizing and the other taking standard deduction. You can't do that. You have to do it the same way.
There is no short form for 2018. A married couple can file separately. The only caveat is that if one itemizes, the other one must. The reverse is also true - if one claims the standard deduction, the other one must. Make sure there's a good reason for you to file MFS. Some credits and deductions are not available on a MFS return.
There is no 'short form/long form'. There is only ONE form. The couple needs to work it out both ways, joint or separate, and see what works for them. It seldom works better to file separate.