Yes. The limit is $4,294,967,295. This is the largest 32 bit unsigned integer. Upon reaching this amount there is some dialog between Homer and Frink. It ends with a notice from EA that the maximum cash has been reached and that you might consider spending some of it on the Sit-N-Rotate or a few thousand Blood Mobiles. The cash number display turns to red numbers indicating the maximum amount has been accumulated and no further money is added.