The only way to report the total loss in the value of your vehicle due to an accident would be to claim a casualty loss. (You can add the loan repayment amounts to the cost basis in your totaled vehicle. Otherwise the IRS will view the loan repayment amounts as nondeductible personal expenses).
You would be able to claim a casualty loss related to your vehicle for the difference between the actual loss (cost of the vehicle less any business depreciation taken on the vehicle) and any reimbursed insurance amount if your reimbursement was less than the actual loss. If no insurance, then the entire replacement cost will be considered the amount of the casualty loss.
A casualty loss is damage, destruction, or property loss resulting from one of these identifiable events:
- Sudden event -- swift, rather than gradual or progressive
- Unexpected event -- ordinarily unanticipated and unintended
- Unusual event -- not a day-to-day occurrence
So, you can only deduct losses not reimbursed or reimbursable by insurance or other means. You'll need to subtract $100 from each casualty loss of personal property. The total of your casualty and theft losses on personal property must be more than 10% of your adjusted gross income (AGI) in order for it to be deductible.
Here is a link for additional information about reporting your casualty loss: Casualties, Disasters and Theft and Casualty Deductions for Federal Income Tax
