Vacation as a deduction
This can be tricky but possible. The IRS tells us that there are ordinary and necessary expenses to consider.
Understand the definitions of both.
You could drive to Niagara Falls for a conference on your product line and then spend a few days there as a vacation.
The miles and other expenses such as per diem Food and Entertainment costs are considered fair for the time that you are at the conference only.
The other times the expenses are yours to pay with no rebate from the IRS. The miles are still OK to deduct and the other related expenses for the conference but not the expenses for the vacation.
Bosses not paying mileage expenses?
There are different methods for a boss to cover the expense of driving costs for employees. Look into the www.FAVR.cc (FAVR ) method.
There are some employers that just pay a small amount to keep you quiet but it isn't really enough to cover the costs associated with running your vehicle all of the miles.
In that case you would be better off taking a mileage allowance or deduction.
Look at this 50 page publication ( It is a PDF file) from the IRS Pub 463 for taking "Travel, Entertainment, Gift and Car Expenses", for your tax filing as it might be appropriate for you.
Also you can use the IRS form 2106-EZ to get a deduction for the "Unreimbursed Employee Business Expenses".
This is the amount that your boss isn't covering for mileage.
If he is paying you half the rate that the government allows for mileage then take the second half from the IRS on your taxes to get coverage for the full amount after all.
Interesting Examples of use variations
If you own six vehicles, say four cars and two vans and all are used in your business you can get the Standard Mileage Rate Deduction for all six vehicles as long as only four of them are ever used at a time.
If you had four trucks in your business and in the middle of the year you traded in two trucks for two new trucks. That shows six in a year but the use is only for four at a time. You can use the Standard Mileage Rate as a deduction.
If you are self employed you can deduct the percentage of interest paid for the year that represents the same percentage of miles driven for business, but if you are an employee of a business you can't deduct interest on your car loan.