Employees can no longer deduct out-of-pocket travel costs in their federal return for tax years 2018 through 2025 per the Tax Cuts and Jobs Act of 2017. You will not be able to deduct your travel expenses for your W2 income unless you meet one of the following exceptions (Armed Forces reservist, a qualified performing artist, a fee-basis state or local government official, or an employee with impairment-related work expenses). Maryland does not have a deduction for travel expenses and in California, employers are required to reimburse you.
You can deduct your work-related travel expenses while you were working as a contractor and received a Form 1099-NEC.
Regarding what state you should pay, each income should be reported to the state where the work was completed. You would have to complete a Maryland resident return and nonresident returns for California and Massachusetts. Maryland will tax the income you received from the other two states, but will also give you a credit for taxes paid to the other states in your resident return.
For more information regarding travel expenses, refer to the links below:
