client purchased light truck Dec 30 2019. uses it primarily for business. self employed. depreciation does not carry forward to his 2020 return.  after reviewing all, i realize a mistake was made on his 2019 return, where all info was entered, but the standard car allowance was used. so, I'm wondering if I can or should amend his 2019 return to show the depreciation, or is there any way i can allocate the depreciation to 2020?