If the loss occurred in 2017 and it’s a personal loss, it may be deductible as a theft loss. The loss is treated as an itemized deduction allowable only to the extent it exceeds 10% of adjusted gross income. Starting in 2018, there is no deduction allowed for personal theft losses. Of course, business losses continue to be deductible.
Generally, itemized deductions for job and investment expenses subject to a 2% of adjusted gross income floor.