Monthly Carryover / Windfall Accounts
In my previous budgeting life, we used windfall accounts which built month by month until we needed the money. YNAB seems to function for this as long as I don't spend myself into a deficit in a category, in which case it seems to wipe the slate clean the very next month. I'd like to see that red number carry over to the following month and our budget for the month to be set against it until we "catch back up." Is there any way to make YNAB do this or must I find the money somewhere in the month in which the expense comes to cover the expense and not carry a negative balance in that category over to the following month?
No. There is no way to have YNAB automatically carry forward a negative in a category from month to month. You can do it by manually entering a -$X amount in the same category when the month rolls over. It's not recommended practice because for those with limited account liquidity, creating false category balances can cause them to inadvertently overdraft or NSF an auto-payment.
I would encourage you to always have positive real numbers that you can totally rely on in your budget. Pretending you have $1,000 in category A, while telling yourself you "owe yourself" $1,000 in category B of future income or future restricted spending, is just a lot of math games. Much better to display zero in both those categories, so you can see exactly where you are at all times.
In YNAB 4 I make use of the “carry over” feature occasionally when a transaction fell on the “wrong side” of the month — e.g. an auto payment scheduled for the 1st of every month fell on the last day of the previous month because of a holiday or some other reason that led it to be processed a little early. I take it this feature is totally gone from the current YNAB, and is one of the reasons I’m still a YNAB 4 user and will be until it totally breaks. (The other reason is the current version’s inexplicable inability to forecast bank account balances based on scheduled transactions. That’s still a thing, right?)
YNAB is an allocation budget, or more accurately an electronic version of envelope budgeting. When your money is physically divided up and put into envelopes, it's not possible to spend more than is in the envelope. So that means you need to use the same solution that a physical envelope budgeter would use. You must pull the extra money needed from some other envelope.
YNAB4 used to allow this. There are plenty of examples where you would want a negative balance. For example, you have an annual bill, and you want to reflect that you are putting money in the envelop leading up to when the bill is due (and hence you have enough to pay the bill). Or, you overspend in one month, you don't have the funds in that month to cover, but you adjust in the next month. By wiping out the negative balances, I have no way of seeing where I am......as I was able to in YNAB4.