I traded my 14 year old car for $500 towards a new car. i didn't use it in 2020 for 3% business use, like i had for the last 14years. would i pay any taxes on $500?

[ColeenD3]

Maybe. If it was fully depreciated, it would have a adjusted basis of zero. If you only used it 3% for business, it might not be fully depreciated.