Section 4401 imposes upon those engaged in the business of accepting wagers an excise tax of 10% on the gross amount of all wagers they accept, including the value of chances purchased in lotteries conducted for profit. Those liable for the occupational tax must register each year. They are required to preserve daily records indicating the gross amount of the wagers as to which they are liable for taxation, and to permit inspection of their books of account. D was convicted for wilfully failing to register and to pay an occupational tax for engaging in the business of accepting wagers, as required by 26 USC 4411 and 4412, and he was also convicted for conspiring to evade payment of the occupational tax. D claimed that the statutory obligations to register and to pay the occupational tax violated his constitutional privilege against self-incrimination. The Court of Appeals affirmed. The Supreme Court granted certiorari.