Major Moves · Debt & Windfalls
Windfall Allocation Calculator
I just got a lump sum — now what?
How This Calculator Works
A windfall — an inheritance, a signing or retention bonus, a legal settlement, an equity payout — arrives as a single number, but the decision it forces is an allocation: how much to high-interest debt, how much to an emergency fund, how much to retirement accounts, how much to taxable investing. This calculator makes that allocation explicit. You set the windfall amount and slide the percentage going to each destination, and it computes the dollar consequences of the mix instead of leaving "I should probably do a bit of everything" as a vague intention.
The reason allocation order matters is that each destination has a different effective return. Paying off high-interest debt is a guaranteed return equal to the interest rate you stop paying — usually the best risk-adjusted use of the first dollars. An emergency fund returns little in yield but prevents forced borrowing or forced selling later, which is a return that never shows up on a statement. Retirement and taxable investing both compound at market rates, differing mainly in tax treatment and accessibility.
The calculator projects the invested portions forward to your retirement date at your assumed return, producing a future-value figure for the mix you chose. Comparing two allocations side by side — say, everything to investments versus debt-first-then-invest — shows the real long-term cost or benefit of each philosophy with your numbers, not a rule of thumb.
Worked Example
Say $200,000 arrives and you're carrying $30,000 of high-interest debt, 20 years from retirement. One reasonable mix: clear the debt entirely (15% of the windfall), put 10% into finishing the emergency fund, and split the remaining 75% between retirement and taxable accounts. The calculator shows the debt payoff saving you every future interest payment on that balance, the emergency fund as immediate stability, and roughly $150,000 compounding for two decades — which at a steady assumed return grows to a multiple of the original amount by retirement.
Flip the mix — keep the debt, invest everything — and the projection often looks slightly bigger on paper, because assumed market returns usually exceed nothing. But it looks bigger only if the debt's interest rate is below your assumed return and you never miss a payment; the comparison makes visible that carrying expensive debt while investing is a leveraged bet, not a free lunch. That's the judgment the sliders are designed to sharpen.
Frequently Asked Questions
What should I do first with a large windfall?
Before allocating anything: park it somewhere safe and liquid, take time to let the emotional charge fade, and understand any tax consequences attached to how the money arrived — an inheritance, a bonus, and a settlement can be taxed completely differently. Then work the allocation deliberately: high-interest debt and a full emergency fund are usually the first claims because their returns are guaranteed, and the invest-the-rest decision can happen on a slower clock.
Is it better to pay off debt or invest a windfall?
Compare the debt's interest rate to the return you can reasonably assume on investments. Debt costing more than your realistic expected return is a guaranteed loss to keep — retiring it is the better 'investment.' Low-rate debt, like a cheap mortgage, is a closer call where keeping the debt and investing can win mathematically but adds risk and psychological load. The calculator lets you run both mixes and see the projected difference rather than arguing from principle.
Do I pay taxes on an inheritance?
Usually not on the inheritance itself at the federal level — estate taxes, where they apply, are generally paid by the estate before assets reach you, and only a handful of states levy inheritance taxes on recipients. What you inherit can still create taxes later: inherited retirement accounts come with required distribution rules, and inherited investments have their own cost-basis treatment. The details depend heavily on the asset type and your state, so confirm your specific situation with a tax professional before making allocation decisions.
Should I put a windfall into retirement accounts if I can't access it for decades?
Accessibility is a real trade-off, not a footnote: tax-advantaged accounts generally grow more efficiently, but money you might need before retirement age belongs in taxable accounts or cash despite the tax drag. A common-sense split covers near-term flexibility in taxable savings and routes long-horizon money toward retirement accounts — and note that annual contribution limits mean a large windfall usually enters retirement accounts over several years, not all at once.
The model behind this calculator
spec v1.0.1 · 250 open casesThis calculator runs a published model: its inputs, formulas, assumptions, and exclusions are documented in a versioned specification, and it is Concordance-tested — an independent second implementation, built from that spec alone, must agree with it on 250 open test cases before any change ships. The same model is callable by AI assistants and developers.