With this setting activated, if you hover your mouse over the Age of Money displayed in the top right of the Budget screen, a (tooltip popup) date will appear showing the date that corresponds with the calculated age of your money.
So if your Age of Money is 90 days, the date displayed with this setting will be 3 months prior the current date.
The general idea of the Age of Money is that it represents the gap between when you bring a new dollar into the budget (as inflow: Ready to Assign/To Be Budgeted) and when that dollar is actually spent on something and leaves your budget. The goal is to age your money like a fine wine.
When YNAB first introduced the Age of Money [AoM] feature, I considered it to be pretty gimmicky. My opinion has mellowed a tad. I’ve learned to live with it. I concede that if you don’t get too caught up in the numbers, the AoM has some value. That said, I think this Date of Money Toolkit setting doubles down on the gimmicky-ness and provides very little real value.
Money is fungible — one dollar spends exactly the same as any other dollar. Features such as the Date of Money encourage or reinforce mental biases and logical fallacies such as mental accounting. Turn on the Date of Money if you want to, but I’d caution you to make an extra effort at self-awareness — why is seeing that date important to you? What emotions or thoughts does that date invoke? Remember, extreme behavior — whether lots of spending or no spending — is often detrimental to your own well-being and as well as to your relationships with others.