Most likely, you're reading this because you saw a negative number in the Budgeted column, and you're wondering — how did that get there?
You're in the right place!
This typically happens when a category has cash left over from a previous budget month, which gets moved to a different category. Let's walk through a scenario.
Cash Left Over
When you select any single category in YNAB, at the top of the right sidebar, you'll see if there was any cash left over from the previous month. Even though it doesn't have its own column in your budget, that money is part of the equation that results in the amount Available for that category.
Here I had $84 left over in the Clothing category at the end of March, which rolled into April—and I decided not to budget any more money, leaving Budgeted at $0.
In fact, I realize I need extra money in my Gifts category for April (lots o' birthdays) and move $34 there, knowing I'll still have $50 left in Clothing:
Same as any time money is moved out of a category, the Budgeted value will decrease by that amount. Since $0 was Budgeted in Clothing, it will decrease to negative $34, whereas the amount Budgeted in the Gifts category will increase from $25 to $59.
Back in the right sidebar of the Clothing category, the full equation is visible:
$84 Cash Left Over From March
-$34 Budgeted This Month
$50 Available This Month
As long as the Available amount is still green, it's all good—there's no reason to worry about that negative number! If it turned yellow or red though, you may want to move some money back.