I live in MD but work in DE. For the credit, should it be my total tax liability to DE or total liability to DE minus the personal exemption amount?

[TomD8]

This is the instruction from line 11 of Maryland Form 502CR, the form used to calculate the other state credit.

Enter the amount of your 2017 income tax liability (after deducting any credits for personal exemptions) to the other state and locality in the other state (where applicable). Do not enter state or locality tax withheld from your W-2 forms.

http://forms.marylandtaxes.gov/current_forms/502cr.pdf