Is the amount of money each player has in Monopoly public knowledge?

In Monopoly, is the amount of money each player has public knowledge? To put it more specifically, if you ask a player how much money they have, are they obligated to tell you?

All transactions are clearly public. You know how much money someone starts with, and every income and expenditure. So, with perfect memory, you could know how much money each person has. But that is not enough to actually answer the question. Just because a value is derivable doesn't make it public. (Settlers of Catan, for example, has hidden hands of resources despite the fact that the resources held by players is derivable information.)

Additionally, if playing on a pre-2008 version, a player would need to reveal how much money they have when tallying their net worth if they land on Income Tax and go for the 10% of net worth option.

The normal game rules do not mention this one way or another.

• Now I wonder if all transactions are indeed public. I've never seen it happen, but I wonder if two players could agree to a trade in secret, swapping property for some undisclosed but clearly non-zero amount of cash. Jun 9, 2022 at 18:13

It's semi-public. A player's set of bills must be visible, but they are not obligated to tell you how much money they have.

This comes from the 2009 Monopoly World Championship rules (emphasis is mine):

Your money must be in view of the banker, judge and other players during play. You can leave it in a pile and even turn it face down, so it’s not clear exactly how much you have, but it must all be on the table – you can’t hide a note in your pocket and put it back into play later.

• You can briefly count your money out of sight of other players (e.g. under the table) before putting it back in full view of others.

• You do not have to tell anyone exactly how much money you have, even if asked.

The best analogue I can think of is points in Small World. You can get a rough approximation from looking at the size of their pile of money, but they can use creative denominations to be misleading one way or another, and unless you've been keeping track, you won't know the exact number.

Thanks to @L.ScottJohnson, this is corroborated by Hasbro Customer Care:

Your money must be in view of the banker, judge and other players during play. You can leave it in a pile and even turn it face down, so it's not clear exactly how much you have, but it must all be on the table – you can't hide a note in your pocket and put it back into play later. You do not have to tell others how much money you have. They can guess based on how big your pile is. -- Rochonda, Global Consumer Care Representative.

Personal note: I was fairly surprised by this answer. It's at odds with how I've played the game.

• In games I have played, players were required to sort their cash by denomination, and tuck the stacks, one for each bill size, half-way under their side of the game board. But you could not demand an exact count of any stack. This was a house rule i guess, but it seems to me not a harmful one. Jun 6, 2022 at 23:12
• FYI: Hasbro.com consumer care is pretty quick about answering email. The official answer matches this answer: "Your money must be in view of the banker, judge and other players during play. You can leave it in a pile and even turn it face down, so it's not clear exactly how much you have, but it must all be on the table – you can't hide a note in your pocket and put it back into play later. You do not have to tell others how much money you have. They can guess based on how big your pile is." -- Rochonda, Global Consumer Care Representative. Jun 10, 2022 at 17:29
• @L.ScottJohnson Thanks for the official corroboration. I've added it to the answer
– Zags
Jun 10, 2022 at 18:18