| Technically your Accountant is correct in that since you jointly owned the property you should be equally sharing the mortgage interest and property taxes between you and your separated spouse.
However, it is worth examining whether or not one of the spouse claiming 100% of the property taxes and interest would benefit more than if both equally shared the property tax and mortgage interest deduction. I would suggest that you provide your separated spouse with an analysis to see what generates the most tax savings and if the latter provides a greater tax benefit, then I would suggest that you encourage your spouse that you should claim 100% of the tax benefit but that you would share the tax benefit with her. | 
