01The fixed monthly budget powers rollover
Start with the minimum payment on every debt entered with a positive balance, then add the recurring extra you can sustain. In the default fixed-budget mode, that total stays in the plan after a debt closes. The freed payment moves to the next target instead of disappearing from the projection.
A zero-interest example makes the mechanics visible. Suppose one $500 debt has a $50 minimum, another $1,000 debt has a $100 minimum, and you add $25 monthly. The regular budget is $175. Snowball clears the first debt in month 7 and the second in month 9. If the first debt’s $50 minimum disappears after closure instead, payoff moves to month 10.
Turning off “Keep total monthly budget fixed” models a different plan: closed debts’ minimums leave future budgets while recurring extra continues. The minimum-only baseline also excludes every recurring, annual and one-time extra.
02Snowball and avalanche answer different questions
Both methods pay active minimums before concentrating the remaining budget. Avalanche targets the highest APR, using smallest current balance and then entry order to break ties. Snowball targets the smallest current balance, using highest APR and then entry order to break ties. If a target closes with money still available, the remainder spills into the next target in the same month.
Avalanche is designed to reduce interest by retiring expensive balances earlier. Snowball is designed to create individual account wins earlier. Neither motivational benefit is guaranteed, and equal interest does not prove that two plans used the same order. Use the actual dollar, month and first-closure comparison rather than a universal rule.
- Choose Avalanche when minimizing modeled interest is your priority.
- Choose Snowball when clearing individual accounts earlier helps you follow the plan.
- If both reach zero in the same month at the same cost, the result is a tie — not a reason to invent an advantage.
03What the projection assumes
For each open debt, monthly interest is the post-windfall balance multiplied by APR ÷ 12 and rounded to cents. Regular payments are then applied. The model holds each APR and entered minimum fixed, excludes new purchases and fees, and caps every final payment at the amount actually due. Month 1 means one monthly payment from today; the calendar result is an estimated month, not a lender due date.
Real credit-card minimums can change as the balance changes, and many lenders accrue interest daily. Promotional rates, deferred interest, late fees, prepayment penalties and new charges can also change the result. Update the inputs when a statement changes and request a dated payoff quote before sending a final lender payment.
- A payment below monthly interest can make a balance grow. The tool names first-month growth instead of hiding it.
- A repeating ledger or a lone remaining payment that does not exceed interest produces a non-payoff warning.
- A 1,200-month guardrail or runaway-balance guardrail means payoff was not established. It never counts as a debt-free date.
04Recurring extra, windfalls and a target horizon
Recurring extra changes every monthly budget. A one-time extra can be assigned to a future month, while annual extra repeats every 12th month. Both windfall types are applied before that month’s interest in the selected strategy order and can spill across several debts. They are reported separately from regular payments in the exported ledger.
The optional goal solver works backward from your chosen horizon. It returns the total recurring extra required, not another amount to add on top of that answer, and it also shows the resulting starting total budget. It does not silently change your current plan.
A sustainable recurring amount is usually more useful than an aggressive number you abandon. Keep essential expenses and an appropriate emergency buffer in the budget before committing surplus to debt.
05Use the schedule as a monthly checklist
The summary answers when and at what cost. The monthly schedule answers how: opening balance, regular budget, regular payment, windfall, interest, principal and closing balance. The debt-level CSV shows exactly where every dollar went for every account, including duplicate labels resolved by stable internal keys.
The Consumer Financial Protection Bureau describes both highest-interest and snowball methods, including continued minimums and rolling freed money into the next debt. Its payoff-amount guidance also explains why a current balance can differ from the amount needed to satisfy a loan on a particular date.