That's because under California law, employers must reimburse their employees for all “necessary expenditures or losses” incurred in connection with their jobs. This means your employer will be also responsible for some of your expenses if you: travel for work, use your own equipment for work, or.
As long as your trip is primarily used for business purposes, and you are traveling away from your place of business for longer than an ordinary day's work, you can deduct 100 percent of your transportation costs, such as airfare or mileage.
Under California law, employers are required to reimburse employees for all necessary business expenses incurred while doing their job. Failure to reimburse those expenses is a violation of California employment law, and your employer may be required to compensate you.