Before 2015, Bt80 tickets were often sold for Bt100 so the junta introduced one-month jail terms or Bt10,000 fines for those responsible.
The original 1974 act imposed up to Bt2,000 fines.
Anyone selling tickets at schools or to under-20s also faces a Bt10,000 fine.
The new law also improves the lottery office's internal structure and the allocation of profits while ensuring access for people with disabilities to lottery ticket retailers.