“My wife’s credit card was stolen, but I’m not going to report it,” a husband says in this old joke. “Whoever stole it spends less than she does.”
 
The joke was cited in print several times in the first months of 1972. It’s not certain who came up with the joke. British-born American comedian Henny Youngman (1906-1998) is frequently credited, but not in the 1970s.
 
 
Google News Archive
3 February 1972, Miami (FL) News, “Miami Confidential” by Herb Rau, pg. 6-B, col. 6:
WIOD’s Tom Adams says his wife lost her credit card—“but I haven’t reported it yet because the guy who found it spends less than she did.”
 
3 April 1972, Omaha (NE) World-Herald, “Strictly Business” comic, pg. 27, col. 1:
(Two men are talking over drinks.—ed.)
“My wife’s credit cards were stolen but I’m not reporting it. Whoever has them is spending less than she did.”
 
7 April 1972, Oakland (CA) Tribune, “Man Alive” by Bill Fiset, pg. 21, col. 1:
And at Solomon Grundy’s a guy at the bar commented that he’d lost a credit card nd someone obviously found it and was using it. “Just report the thing lost,” said the bartender. “I’m not about to report it lost,” the guy said. “The woman who found it spends a lot less than my wife.”
 
25 May 1972, Burkburnett (YX) Informer, ‘Editor’s Viewpoint” by Raymond Greenwood, pg. 1, col. 1:
I recently heard of a fellow who had lost a credit card, but would’t report it to his company. “The woman who found the card,” reported the man, “spends less money than what my wife did.”
 
13 June 1974, The Times-Picayune (New Orleans, LA), “House Votes to Consider Lowering Interest Rates” by John LaPlace, sec. 1, pg. 22, col. 1:
Rep. W. J. Tauzin of Thibodaux said he favored lowering the interest rates.
 
“Someone stole my wife’s credit card the other day, and I haven’t advertised to get it back yet because whoever’s got it charges less than my wife,” Tauzin said.
 
23 April 1978, Boston (MA) Herald American, “Behind the Tube” by Jean McNeil, Television, pg. 2, col. 2:
On a “Mike Douglas Show,” comic Corbett Monica commented: “My wife’s credit card was stolen, but I didn’t report it. The thief spends less than she did.”
       
Google Books
The New York Friars Club Book of Roasts:
The Wittiest, Most Hilarious, and, Until Now,  Most Unprintable Moments from the Friars
By Barry Dougherty
New York, NY: M. Evans
2000
Pg. 103:
“My wife lost all her credit cards. I’m not gonna report it; the guy who found it spends less than she does.”
(Henny Youngman.—ed.)
 
Google Books 
The Mammoth Book of Comic Quotes
By Geoff Tibballs
London: Constable & Robinson Ltd.
2004
Pg. ?:
My wife lost all her credit cards, but I’m not going to report it. Whoever found them spends less than she does.
HENNY YOUNGMAN
 
Twitter
Jewish Comedians
‏@JewishComedians
Henny Youngman: Someone stole all my credit cards, but I won’t be reporting it. The thief spends less than my wife does.
3:32 PM - 23 Feb 2015