If you file a joint tax return, then for tax purposes you both own the condo and can deduct the taxes. Generally you can file a joint tax return for the tax season in which your spouse died. Assuming that you inherit the condo you can continue to deduct the taxes you pay even if it takes some time to update the deed. If for some reason your spouse left the condo to someone else, then you can't deduct any taxes you paid after his death, they would be deductible by the new owner (who should reimburse you).
