What to do with the money you didn't spend this month

Money you didn't spend this month should go to one of two places, decided before the month ends. If it came from a category that is lumpy, such as car repairs or gifts, it stays in that category and carries forward, because the expense it was for hasn't arrived yet. If it came from a category that is steady, such as groceries or gas, it is a real surplus, and it should move to savings or debt with an actual transfer. The one thing not to do is leave it unassigned in checking, where it blends into next month's pay and gets spent twice.

Why leftover money disappears by the 10th

A monthly budget that resets on the first treats last month's discipline as gone. The $180 you didn't spend is still in checking, but the budget shows a fresh month with full amounts, so the balance looks $180 richer than the plan accounts for. Nobody decides to spend it. It goes in a slightly larger grocery run, a dinner that would have been a lunch, and a purchase that was "already covered", and by the 10th the cushion is gone with nothing to show for it.

The fix is not a stricter budget. It is a decision, made once a month, about where the leftover goes, so that next month's checking balance and next month's plan agree with each other.

Sort the leftover by where it came from

Every category is one of two kinds, and the kind decides what happens to what's left.

• Steady categories cost about the same every month: groceries, gas, utilities, dining out, subscriptions. What's left in them at month end is a genuine surplus. You spent less than planned, and the money is free.
• Lumpy categories cost nothing most months and a lot in one: car maintenance, medical, gifts, clothing, home repairs, annual renewals. What's left in them is not a surplus. It is a partial fund for an expense that hasn't arrived, and spending it means the expense lands unfunded.

The rule follows from the kinds: carry forward in lumpy categories, sweep from steady ones. A carried balance in a lumpy category grows until the expense comes, which is the point. A carried balance in a steady category is a cushion with no purpose, and it lets the category drift upward without anyone noticing.

The end-of-month sweep, step by step

1. Write each category's budget and spending for the month, and the difference. Do this from statements, not memory, and include the categories that went over.
2. Mark each category steady or lumpy. When in doubt, ask whether a month with nothing spent means you saved money or means the bill hasn't come yet.
3. Carry the lumpy leftovers forward. Add each one to that category's balance for next month. A category that went over carries a negative balance the same way, which reduces what's available until you make it up.
4. Net the steady categories. Add their leftovers together and subtract their overspending. The result is the month's surplus on paper.
5. Check the cash, then move the surplus with a transfer. Before anything moves, checking has to cover what is already spoken for: the bills due before the next paycheck, the everyday spending until then, the card balances you have not yet paid, and the positive carried balances, with nothing counted twice. What remains above that is the most you can sweep, and a month whose income came in short can be under budget in every category and still have nothing to move. Then transfer it the same day to a named destination: the emergency fund, a specific debt, or a goal. Money that stays in checking with a savings label is not saved.
6. Write the carried balances down where next month's budget will show them, so the cash they represent reads as reserved rather than available.

A worked example

A month with seven categories, a $1,260 budget, and $1,026 spent. The $234 left over is sorted by kind.

The steady categories net to $52 minus $40 plus $29, which is $41, and that amount leaves checking for savings. The lumpy categories hold $193 between them, and next month each starts with its carried balance plus its new amount. The two figures add back to the $234 that was left, so nothing is unassigned.

Three months later, with nothing spent on the car, the car maintenance balance reads $300. A $280 brake job then lands on a category that has it, in a month that doesn't have to absorb it.

Keep a carried balance honest

A carried balance is a claim on cash that has to exist. The positive carried balances, added together, should fit inside the checking balance after the bills due before payday and the card balances not yet paid, with a bill that a balance already funds counted only once, or the budget has promised the same dollars twice. Check the two figures against each other once a month; if the balances exceed the cash, something was spent that the budget still counts as reserved.

Overspending carries too. A lumpy category that goes $200 over in the month its expense lands carries a negative $200 into the next month, and the balance stays below zero until the monthly amounts make it up. That is the honest picture, and it is better than resetting the category and pretending the overspend didn't happen.

Balances can also grow past their purpose. When a category's carried balance exceeds what a full year of that expense would cost, the monthly amount is too high. Sweep the excess to savings and lower the amount.

Common mistakes

• Treating the leftover as a raise. It is one month's surplus, not a new level of income, and next month may run the other way.
• Rolling over every category. Steady categories accumulate a cushion with no purpose, and dining out quietly drifts from $250 to $320 with the balance covering the difference.
• Rolling over nothing. Lumpy categories then read as over in the one month the expense lands, and the budget looks broken twelve times a year.
• Sweeping without the transfer. A surplus that stays in checking is spent by the 10th, as above.
• Resetting an overspent category. The overspend came out of real cash, and the budget should show where.
• Doing the sweep from memory. The steady categories net out to small numbers, and small numbers are easy to get wrong without statements.

Common questions

Should I roll over unspent money or reset every month? Both, by category. Roll over the categories where a month with nothing spent means the expense is still coming, and reset the ones where it means you spent less. A budget that does one or the other for every category gets half of them wrong.

Does overspending carry forward too? Yes, if the category rolls over. A category that goes $60 over starts next month $60 down, and the monthly amount fills the hole before anything is available. In a category that resets, the overspend came out of the month's steady surplus, which is why the sweep nets the two.

Is leftover money the same as savings? Only after it moves. A carried balance in a lumpy category is a bill in slow motion, and a steady surplus that sits in checking is spending money with a delay. Savings is money that left the spending account for a named purpose.

What if I'm paid every two weeks and some months have three paychecks? Treat the third paycheck as a steady surplus decided in advance: assign it to a destination before it arrives, and move it the day it lands. It is the largest leftover most people ever have, and the one most often absorbed by nothing in particular.

How big should a carried balance get? Up to what the expense costs when it arrives, with a little margin. A car maintenance balance that reaches a year's worth of repairs is over-funded; lower the monthly amount and sweep the excess. See How to budget for bills that aren't monthly for sizing the monthly share of a known bill.

How Zypper handles this

Zypper makes the rollover decision a per-category switch. In a category's settings on the budget page, turn on Roll over unspent budget, choose the Rolling over since month the balance starts accumulating from, and optionally enter a Starting balance for money you had already set aside, so a mid-year setup begins funded. The row then reads Rolls over, and a rollover chip beside the amount shows the balance carried into the month, green when it is positive and red when overspending has pulled it below zero. The balance is recalculated from your transactions every time the page loads, as the starting balance plus each month's budget minus each month's spending, so a recategorized transaction changes it and a refund adds back. Categories left on the default reset each month, which is the steady-category behavior above, and the summary card's equation shows the total carried across your categories. Choosing a cadence of every three months or longer turns rollover on for you, since the budget has to accumulate between occurrences. See Rolling over unspent budget and Creating your budget for the details, or get started with Zypper to see your own carried balances.