One lump sum. Zero leaks.

Because unassigned money gets absorbed by everyday spending — a bigger grocery run here, a "we earned it" splurge there. Psychologists call it mental accounting: a lump sum feels like bonus money, not real money, so the usual rules switch off. The fix isn't willpower, it's speed and assignment. Give every dollar a job and move it out of your spending account within 48 hours, before the leak starts.

Every windfall plan in this tool reserves a slice — 10% on the aggressive presets, 20% on the balanced one — as a designated guilt-free reward. Plans that demand 100% sacrifice almost always collapse into a revenge-spending binge that wipes out the progress. A planned reward makes the other 80–90% stick: you get to enjoy the money on purpose, in a fixed amount, instead of leaking it everywhere by accident.

Any money that lands outside your normal paycheck rhythm: a tax refund, a work or safety bonus, retro/back pay from a corrected rate, overtime settlements, a tax credit, an insurance payout, a gift, or selling something big. If it arrives as a lump sum and wasn't in this month's budget, it's a windfall — and it deserves a routing plan before it touches your spending account.

It depends on your foundation, which is why Step 2 exists. With no $1,000 starter cushion, one emergency sends you straight back to a credit card — so the buffer usually wins first. With debt over 20% APR, the interest bleed is so expensive that the surge strategy wins once a basic cushion exists. Behind-schedule sinking funds are tomorrow's debt in disguise, so catching them up counts as savings that prevents borrowing.