Let’s say your salary was paid entirely or partially in Virtual Currency. The United States considers the Dollar valuation of what you were paid, at the time of payment, as taxable income. A salary of $30,000 in virtual currency is taxed the same as $30,000 paid in USD.
It’s good to ask your employer/contractor for the fair value of the virtual currency you received, in order for you to get the most accurate figure for what you owe. If the fair value is unknown, you would use the USD value of your virtual currency at the time of your filing.