That’s right. Nothing about plastic model kits (again). Somebody should turn me in to the authorities.

Marilyn Vos Savant (Savant? Really?) writes a column for the ultimate old-people magazine–the one called “Parade” that comes in the Sunday paper. She is the world’s smartest woman, obviously, because she has parlayed a high IQ into a career without having to do much other than answer trivia questions.

Marilyn vos Savant. World’s smartest person.

That, my friend, is brains.

Now, I think of myself of being one of the smartest people on the planet, and I’m aware that telling people how smart you are is not smart. It causes them to want to hit you with a hammer until you stop moving or making those whiny sounds. But I have been interested in Ms. vos Savant since I discovered “The Monty Hall Problem” through her column. The Monty Hall (a.k.a. “game show problem”) is probably the best brain-twizzler ever invented. I got it wrong when I read about it the first time, but so did Paul Erdős.

But we’re not here to talk about THAT puzzle. We’re here to talk about this one, which appeared in Ms. vos Savant’s column a couple of weeks ago.


Joint Checking Accounts 
December 3, 2017 – 5:00 AM
By Marilyn vos Savant 

My wife and I contribute equally to our joint checking account. Also, I sometimes pay for shared expenses myself, and she pays me back half. One time, she put $1,000 into the joint account, but instead of matching it, I suggested that she just not pay me back for her half of $2,000 of shared expenses that I had paid myself. This seemed fair at the time, but I’m starting to wonder about it. Did somebody get the better end of the deal?

—Steven S., Honolulu, Hawaii

Marilyn responds:

Yes, your wife did. The joint account gained $1,000, and $2,000 in shared expenses were paid. Of this $3,000, your wife contributed $1,000, and you contributed $2,000.

Yeah. Well, I went to her website and looked around and found a forum, and I was surprised that a bunch of washed-up old accountants hadn’t explained the answer six-ways from Sunday. Instead, the forum people (people hang out at her forum??) agree, sort of, that Mrs. S. owes Mr. S. a thousand bucks.

I’m sure this is a misunderstanding. Marilyn was a bit vague on this one. I think she meant that Mrs. S. owes Mr. S. FIVE HUNDRED dollars American, not a thousand. The answer “she owes him a thousand dollars” is wrong. That amount, if it’s the amount she should pay him, is double the actual amount she owes. So it’s wrong, you dig?

Now, I spent some years earning a living doing financial accounting. I could get all technical on you and explain why this is true, but instead I’ll try to act like a human being.

Let’s assume that nothing “unusual” happened, that Mrs. S. has plenty of cash in her personal account and so does Mr. Trump, uh, I mean “Mr. S.” Let’s say that she just pays Mr. S. the thousand that she owes him for the joint expenses, and he then, turns around and gives her back one thousand dollars, to “pay her” for her contribution to the checking account. He just hands her the cash and says “have a good time.”

Is this right? Of course not. He does not owe her because she put money in the checking account. He has an obligation to match her contribution, which is a very different thing. Because neither of these people are accountants (I hope) they have this set up in a confusing way. They (properly) have a system where they share payments of joint expenses, but they (improperly) have a system of “matching” for the joint checking account. That’s the source of the problem. When he pays a two thousand dollar expense, she incurs a thousand dollar debt to him, automatically. She should pay it, sooner or later, directly to him.

On the other hand, when she puts a thousand dollars in the checking account, they handle it differently and foul it up. They each “match” the other person’s contribution. When she puts a thousand in there, he must put a thousand in. He can’t hand the money directly to her and say “we’re square.” The money MUST go in the checking account because that’s the only way a “matching” system can work.

The problem with having a “sharing” system and a “matching” system is that, sure as hell, you’re going to mingle the money and start mixing up the systems, and this leads to the confusion that led to the letter to Marilyn. An accountant would (should) tell them to stop this and use a “sharing’ system for all joint activity. That way, every time one partner puts in some money, either to pay an expense or to fatten up the checking account, then the other partner incurs a debt for half that amount, to be paid directly to the other partner. So when Mr. paid two grand into expenses, she owes him a thousand. When Mrs. paid one grand into checking, he owes her five hundred. To simplify, over dinner with wine and candles, he doesn’t say “just call it even.” He says “we’ll count the five hundred I owe you on the checking contribution against the thousand you owe me on the expense payment–so you only owe me five hundred now, baby” or something like that.

What bothers me about this whole thing is that for years I could have been swindling people using this simple device, and I didn’t. Even Marilyn von Savant didn’t figure it out. If only Bernie Madoff had thought of this, people would still be running around Manhattan smiling to themselves as Bernie cleaned out their accounts.


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