u/Southern-Nail3455

Most budget systems I've tried have the same problem: if I blow my budget in March, April starts fresh. The overshoot has no consequence. I tell myself "I'll do better next month" and then don't, because there's nothing that forces it.

About a year ago I tried something different in a spreadsheet, and it actually changed my behavior.
Here's the idea: I picked a discretionary spending category (entertainment: dinners, drinks, fun stuff) and gave myself a monthly allowance. But instead of resetting each month, the balance carries forward. If I overspend $200 in March, April's allowance is $200 smaller. If I underspend $100 in March, April's is $100 bigger. The balance has memory.
This sounds small but it changes everything at the point of decision. Before buying drinks I'm not asking "what's my monthly budget", I'm asking "what's my actual current balance, after months of carry." Sometimes it's negative. When it's negative, I can't spend on this category until I recover. The discipline shows up where it matters: before I tap my card.

Some things I learned from a year of running this:

• The rolling balance is what makes it work. Without it, it's just another budget that resets and gets ignored. With it, there's a real consequence to overspending and a real reward for underspending.
• It's a cap, not a target. The rule says "don't spend more than X on entertainment." It doesn't say "spend X on entertainment." Some months I'm well under and the balance banks. That's the point.
• I size the cap as a percentage of my net worth (4%, divided by 12 for monthly), which means when my finances are doing well I have a bigger cushion and when they're not I tighten up. Other people might prefer a percentage of income, or a fixed dollar amount. The mechanic works with any source.
• It doesn't replace a real budget for fixed costs (rent, utilities, food). It's specifically for the discretionary stuff where I was bleeding money without realizing it.
• Categorization is fuzzy. Is a nice dinner "entertainment" or "food"? I pick one and move on. The rule survives ambiguity because it cares about totals.

Has anyone else built a custom system like this? Curious what others have tried. The rolling-balance idea seems obvious but I haven't seen it.

Most budget systems I've tried have the same problem: if I blow my budget in March, April starts fresh. The overshoot has no consequence. I tell myself "I'll do better next month" and then don't, because there's nothing that forces it.

About a year ago I tried something different in a spreadsheet, and it actually changed my behavior.

Here's the idea: I picked a discretionary spending category (entertainment: dinners, drinks, fun stuff) and gave myself a monthly allowance. But instead of resetting each month, the balance carries forward. If I overspend $200 in March, April's allowance is $200 smaller. If I underspend $100 in March, April's is $100 bigger. The balance has memory.

This sounds small but it changes everything at the point of decision. Before buying drinks I'm not asking "what's my monthly budget", I'm asking "what's my actual current balance, after months of carry." Sometimes it's negative. When it's negative, I can't spend on this category until I recover. The discipline shows up where it matters: before I tap my card.

Some things I learned from a year of running this:

• The rolling balance is what makes it work. Without it, it's just another budget that resets and gets ignored. With it, there's a real consequence to overspending and a real reward for underspending.
• It's a cap, not a target. The rule says "don't spend more than X on entertainment." It doesn't say "spend X on entertainment." Some months I'm well under and the balance banks. That's the point.
• I size the cap as a percentage of my net worth (4%, divided by 12 for monthly), which means when my finances are doing well I have a bigger cushion and when they're not I tighten up. Other people might prefer a percentage of income, or a fixed dollar amount. The mechanic works with any source.
• It doesn't replace a real budget for fixed costs (rent, utilities, food). It's specifically for the discretionary stuff where I was bleeding money without realizing it.
• Categorization is fuzzy. Is a nice dinner "entertainment" or "food"? I pick one and move on. The rule survives ambiguity because it cares about totals.

Has anyone else built a custom system like this? Curious what others have tried. The rolling-balance idea seems obvious but I haven't seen it in any of the major budget apps.

Been doing this for about a year and figured I'd share since I haven't seen anyone else do it quite this way.
Every month I check my net worth, take 4% of it, divide by 12. That's my entertainment budget for the month: dinners out, drinks, gifts, movies, anything fun. If I overspend, next month's budget shrinks by the overshoot. If I underspend, it banks. The balance just keeps rolling.
The 4% is the FIRE safe withdrawal rate. Felt like a reasonable cap on fun money, if I'm comfortable drawing 4% forever in retirement, I'm probably not eating my future by spending the same on having fun now.
What I didn't expect was how different this feels from a normal budget that reset every month, so overspending has no real consequence, you just promise to do better in April. With the rolling balance, if I go nuts in March, April starts red. I have no fun budget that month. The discipline shows up where it actually matters, which is before I tap my card.

A few things I've noticed:

• It actually changes behavior at the point of decision. I check the current balance before buying drinks, not after.
• Net worth dropping (bad market) shrinks my fun budget. Feels right. Most budgets pretend market crashes don't exist.
• Categorization is fuzzy and that's fine. Is buying flowers "entertainment"? idk. I pick one and move on. The rule survives a little drift because it cares about totals.
• What counts as net worth is a real decision. I don't include my pension (can't actually spend it).
• I include cash, brokerage, crypto, debts. The "available for fun" net worth is smaller than total wealth, by design.

I've been running this in a spreadsheet and it works but the friction is real, I have to remember to carry the balance forward each month, I've messed it up a few times, categorization drifts. I'm a developer so I built an iOS app around it. Not pitching it here, just being honest about where this is going. Mention it because I could use some beta testers who are good with money.
Anyone else do something like this? Curious how people structure their discretionary spending rules. The 4% feels conservative to me but I've stuck with it because going higher feels like cheating.