I just realized I never took special depreciation back in 2019 for a vehicle I purchased for my business. I filed those taxes on June 25, 2020. Is it too late to amend?

[Critter-3]

No it is not too late however if you used the actual expenses option and entered the car as an asset that may have already been done.  Review the depreciation worksheet carefully.

If you used the standard mileage rate  then you don't get to use the depreciation expense. 

[Opus 17]

If you had an extension in 2020, the deadline for an amended return is October 15, 2023.  If you did not have an extension, the deadline is June 25, 2023.  I don't know if you can use Turbotax to e-file an amended return that far back, but tax professionals may be able to e-file for you.  If you file by mail, use a service with proof of mailing and proof of delivery.

Also as noted, if you have been taking the standard mileage allowance, that includes depreciation, so you can't go back and take special depreciation.  If you have been using the actual expense method and included depreciation in 2021 and 2022, you would have to also amend those years to remove that depreciation or recalculate it based on the special depreciation in 2020.  

[crews268]

Thank you. Would this be a form 3115 amendment, or 1040-x?

[Critter-3]

It would be a 1040X and you will also have to amend the 2020, 2021 & 2022 returns appropriately.   Or you would file a 3115 on the 2023 return you file next January.   I would check first ... if you did take the depreciation by using the actual expenses option then the bonus depreciation would have already been taken ... and since autos are 5 years properties then amending 3 tax years to take something that will be finished next couple of years seems like a giant waste of time.