No insurance?

Yes he has insurance but didn't want to use it because it would increase his rates.  The deductible would have been $1000 for a $1800 accident.  He just paid it out right. It was a hit and run. .  

You can't get a flat tire while driving for business and expect the replacement tire to only be used for business. 

So its a repair like any other repair. whether it was due to driving business or personal miles, the vehicle is used for both.

That makes sense.  Would you have any source code for that or reference so  I can put in the file?  Thank you for answering!

See IRS Pub 547

Failure to file a claim for reimbursement. If your property is covered by insurance, you should file a timely insurance claim for reimbursement of your loss. If you don’t file an insurance claim, you can’t deduct the full unrecovered amount as a casualty or theft loss and only the part of the loss that isn’t covered by your insurance policy is deductible.

OP wants to deduct as Repairs, not as a casualty loss.

By that same logic, if it happened on a personal trip you wouldn't use any of the expense to compute the business use of the auto.

@sjrcpa 

And I want to deduct that bribe I paid the cop for not giving me a speeding ticket, as a donation to the FOP.

So are you saying that if you were in an auto accident while driving the auto for personal use, you couldn't apply the 70% business use percent at year end to the repair fees?  If that is the case, you should be able to deduct it at 100%?

I think she is saying the deduction % changes to zero.

Right, so 0% expensed for business deduction if driving it for personal.  So the same should be true for business.  100% if driving it for business and 0% for personal. 

I believe @sjrcpa is saying the logic is flawed either way. Regardless of whether it was on business trip or not, the same % would apply. 

After the accident, did the client ever use part of the repaired car for personal use, or did they just drop off the repaired part to drive it for personal use? 

I can only say - Nice try.

Some people are trying to have a dry January.  That can be difficult when others don't want to have a January free of tax discussions with "logic" being mentioned.  

Don't forget the many people using that four letter F*** word that is sooooo inappropriate.

That's not FAIR.

The personal vehicle still is a personal vehicle with mixed use; this is not a 100% business accident. This would be like trying to state: I use it 50% for business, so two tires are business and two are personal, when I buy them. Nope. It's all part of operation and maintenance.

Keep in mind you don't deduct costs to restore an asset as if they are Operating expense. That's the main flaw I see here in your logic. You also didn't state if this is being depreciated or using Mileage Allowance for tax reporting.

The Mileage Allowance rate covers the cost of operations including maintenance and repairs.

Actual Costs would make this is an improvement, to restore the vehicle as an asset to its prior status and utility. Of course, it also depends on that total $.