Unless he's a multi-millionaire who has one of the worst tax preparers in history, he doesn't have a 40% tax rate.
The reason why he thinks his tax rate is 40% is because he's making the mistake that common among financial illiterates, which is confusing the maximum tax rate with the marginal (i.e., actual) tax rate.
The highest Federal tax rate is currently 35%. That bracket applies to people who earn $379,150 or more. But if you earn $379,151, that means that only one of the many dollars you earned is actually taxed at the 35% rate.
Similarly, the highest California tax bracket is currently 11%, for people who earn a million bucks a year or more. But again, only the income that's above $1 million is taxed at that rate. Your first $47,000 in income is going to be taxed at the rate of 0 percent to 10 percent.
And that doesn't even factor in deductions. So even if your income is a million bucks a year, it doesn't mean that your combined state and federal tax rate is 40%.