Methods and systems for verifying a derived clock using assertion-based verification. The method comprises counting the number of full or half cycles of a fast clock that occur between the rising edge and the falling edge of a slow clock (i.e. during the ON phase of the slow clock); counting the number of full or half cycles of the fast clock that occur between the falling edge and the rising edge of the slow clock (i.e. during the OFF phase of the slow clock); and verifying the counts using assertion-based verification.