“A fool and his money are soon parted” is a popular English proverb that dates to the 1500s. A fool and his money are soon audited” is a jocular variation on the saying that has been cited in print since either 1968 (if the Google Books date is correct) or 1971.
 
Other sayings from the same proverb include “A fool and his money are lucky enough to get together in the first place,” “A fool and his money are soon elected” and “A fool and his money are soon partying.”
         
 
Google Books
Editor & Publisher
Volume 101
1968
Pg. 50:
“A fool and his money — are soon audited by the Internal Revenue.”
 
17 October 1971, Altoona (PA) Mirror, “IMP Buttons” by Talbert, Family Weekly, pg. 23, col. 2:
A fool and his money are soon audited
 
Google Books
The New Official Rules:
Maxims for Muddling through to the Twenty-First Century
By Paul Dickson
Reading, MA: Addison-Wesley Publishing Company
1989
Pg. 46:
Chensky’s Trueisms. (1) A carpenter always writes on a board. (2) A fool and his money are soon audited. — Ed Chensky, Riverside,
 
15 April 1989, Greensboro (NC) News & Record, “Today’s Chuckle,” pg. 1, col. 1:
A fool and his money are soon audited.
 
16 December 1994, Los Angeles (CA) Times, “Laugh Lines,” pg. 3:
“A fool and his money are soon audited.” (Bob Vogel)
     
Twitter
TFMCentre
‏@TFMCentre
A fool and his money are soon audited #finance #money #business
10:01 AM - 18 Aug 2009
 
Twitter
bullethq_botty
‏@bullethq_botty
@lmhiniature A fool and his money are soon audited.
8:50 AM - 10 Mar 2016