Hello, I was just wondering if there was a specific mod or tuneable I could use to increase the household funds limit from 99,999,999 to the maximum value of a 32-bit integer, just in case I end up getting too rich on my current save file.

Thanks.

I don't know, but you could have your sims invest in Ani's buyable moneybags http://nraas.wikispaces.com/Buyable+Moneybag
As long as you remember to cash in instead of drag and drop selling they hold their value, so if you are approaching the limit of your household funds available they would be something you could buy that gets you back to well below the limit. (You could even make a hidden treasury to pile them in, since the household funds are just money sitting around, and the money bags are also just money sitting around.)