I'm wondering if a percentage discount should be applied to the share of gross value of the property, or to the net after mortgage balance.

Seems to me the discount should apply to the share of gross, and then subtract the share of mortgage debt from the discounted value.

But one appraiser says that's wrong, the discount should come after subtracting the mortgage.

For estate tax reporting, the FMV, which would have included any discount, will then be reduced by the mortgage to arrive at the net assets to be taxed.

These are really two different issues.