Once you inherit and are over the threshold CAT is due on the amount over the threshold. There are two payment dates for CAT on inheritance 1st Jan to 31st August is due in October same year or inheritance in the latter period is 1st Sept to 31st Dec due the following October.... Whether you receive anything right now or not, once 80% and over of threshold is inherited, you are obliged to file and pay..... I am not sure about any rule of how you can or cannot pay it with, inherited cash, I'm sure revenue will accept payment but best to let someone else answer....