Yes, since you are filing a joint return and you both contribute to the costs of the home, you can claim the home expenses related to your qualified home office.  

Thanks!  Do I base it on the entire amount of my contribution.  For example if mortgage interest is $10,000 do use the sqft percentage times the $10k or times $5,000 - my half of the contribution?

You should use the full mortgage interest ($10,000) multiplied by the sqft percentage.

Are you self-employed, or a W-2 employee?

self employed, llc