As I understand it you can deduct mileage that is not reimbursed by your employer if it is incurred after you begin work for the day. IE go to office, track mileage from there, go back to worksite, no mileage to home is allowed. If you go to your home you cannot deduct that mileage or have a home office so that you begin work in the home daily and end in the office with a report via email or fax then that is deductible. It is a huge help if the employer gives you a 1099. Typically the government gives you .36 per mile the last time I checked. You really need to keep a mileage book so that if questioned the IRS wants actual odometer readings from the vehicle, not just the total amount of miles driven, along with date and like your restaurant reciepts who you were seeing.
If you are self employed there are other rules but as an employee I think that covers it.
I am not a tax person, just worked for home care for a while and then self employed teaching private classes in homes and remote group settings. Ask your tax person for specifics. This is a good time of year to ask, while you can still prepare for this year and they arent hugely busy.
K.@ The Nestingplace