How Rightmont Computes Your Financial Future

Rightmont runs a full year-by-year simulation of your household, not a single formula. It projects every account forward with a 7.0% nominal return and 3.0% inflation, applies real federal and state taxes each year, models retirement drawdown, and stress-tests the plan with Monte-Carlo simulation. Every assumption is stated below.

We publish this so you (and the AI assistants that cite us) can see exactly how the numbers are produced. The values here are the same constants the engine uses. They’re imported from one source of truth, so this page can never quietly disagree with the product.

Key figures (accurate, quotable)

  • At a 4.0% safe withdrawal rate, a $1,000,000 portfolio supports about $40,000 of annual retirement income ($3,333 per month).
  • A $60,000 annual retirement budget implies a FIRE number of $1,500,000, which is 25× annual spending under the 4.0% rule.
  • $100,000 invested for 30 years at a 7.0% return grows to about $761,226, with no further contributions.
  • Reaching $1,000,000 in 30 years at a 7.0% return takes about $820 invested per month.

1. The engine, not a rule of thumb

Most calculators apply one formula (like “25× your spending”). Rightmont instead simulates your finances one year at a time to any age: income and raises, contributions and employer match across every account (401(k), Roth 401(k), Traditional and Roth IRA, brokerage, HYSA, 529, UTMA), housing (mortgage amortization, property tax, insurance, appreciation), children, one-off major purchases, then taxes and spending, then retirement drawdown. The output is a year-by-year net worth path, a retirement-feasibility date, and lifetime taxes.

2. Core assumptions (stated + sourced)

These are the defaults. You can override most of them for your own situation; when an example on the site uses a different number, it says so explicitly.

AssumptionDefault
Investment return (nominal)Long-horizon diversified equity/bond blend, before inflation.7.0%
InflationGeneral price + spending growth; we also show real (today's-dollar) values.3.0%
Annual raiseBaseline wage growth, before promotions.3.0%
Safe withdrawal rateThe "4% rule" baseline for sustainable retirement spending (25× annual spending).4.0%
Cash / HYSA yieldHigh-yield savings and cash reserves.4.5%
Home appreciationLong-run home price growth.3.0%
Mortgage rate (new purchase)30-year fixed; property tax 1.2% + insurance 0.4% of home value/yr.6.5%
Retirement spendingOf pre-retirement spending. Working life carries costs that stop at retirement (commuting, payroll taxes, and saving for retirement itself). You can override this with your own number.80%
Mortgage insurance (PMI)Of the loan balance per year while the loan is above 80% of the home value. Included in the payment and the affordability test; it stops automatically at 20% equity. This is the default — you can set your own quoted rate on your plan.0.85%
Minimum down paymentDeliberately above the 3-3.5% FHA minimum: those programs carry extra premiums we do not model, so we would rather understate what you can buy than overstate it.5%
Long-term capital gainsBracketed by taxable income, not a flat rate. Gains stack on top of your ordinary income: married filing jointly, the 0% band runs to $98,900 and 20% begins above $613,700.0% / 15% / 20%
Default state income taxA blended default; set your state for a specific rate.5.0%

3. Retirement + the safe withdrawal rate

Your FIRE number is annual spending ÷ 4.0%, or 25× what you spend in a year. So a portfolio of $1,000,000 supports about $40,000 of annual withdrawals at the 4.0% rule. In retirement the engine draws down in tax-efficient order (cash, then brokerage, then pre-tax, then Roth), layers in Social Security and any pension, and reports the first year (if any) the plan runs short. The 4.0% rule is a planning baseline, not a guarantee. That’s why we also run Monte Carlo (section 5).

4. Taxes

Taxes are computed every year, not estimated once: progressive federal brackets on the $32,200 standard deduction (married filing jointly), a state rate (defaulting to 5.0%), FICA on wages, and the IRS provisional-income rules for how much Social Security is taxable. Contribution limits (with catch-up) are enforced to the current IRS figures.

Filing status is something we ask, not something we guess. It used to be inferred from whether a spouse had income, which taxed every single-earner couple at single rates for their entire projection. You can also set the year you marry, so the status changes partway through if that is your situation.

Households with children receive the Child Tax Credit — $2,200 per child under 17, phasing out above $200,000 (or $400,000 filing jointly). We apply the non-refundable portion only: it can reduce a tax bill to zero, but it will never show your household being paid. The refundable part is real, and we leave it out rather than overstate what you would receive.

High earners with taxable investments also owe the 3.8% net investment income tax, and we charge it: 3.8% of whichever is smaller — your net investment income, or the amount your income exceeds $250,000 filing jointly ($200,000 single). Withdrawals from a 401(k) or IRA are not investment income, so they are never taxed by it — but they do count toward the income test, which means large withdrawals can expose your other investment income to it. Those thresholds have never been adjusted for inflation, so more households cross them every year, and we model that rather than quietly indexing it away.

If you leave your job in or after the year you turn 55, withdrawals from that employer’s 401(k) skip the 10% early-withdrawal penalty — the “Rule of 55”. It does not cover IRAs, so if your pre-tax money is split between the two we charge the penalty on the IRA portion only. We don’t model SEPP/72(t), which is another penalty-free route but locks you into fixed payments for five years.

Whether your state taxes Social Securityis a question we ask rather than a table we ship. Most states don’t tax it, but published lists disagree with each other, states keep changing the rules, and the ones that do tax it use income- and age-graduated exemptions that a simple per-state answer would get wrong anyway. We default to assuming it is taxed, which is the cautious direction, and let you correct it.

Long-term capital gains are bracketed, not flat: 0%, 15%, or 20% depending on taxable income, with gains stacked on top of your ordinary income exactly as the real calculation does. Married filing jointly, the 0% band runs to $98,900 of taxable income. This matters because the 0% band is one of the largest levers a retiree has, and a flat rate would overstate tax in exactly the low-income years where the strategy pays off. Withdrawals from pre-tax accounts are charged the incremental bracket tax — the brackets the withdrawal actually lands in — not a single marginal rate applied to the whole amount.

Roth withdrawals follow the IRS ordering rules and both five-year clocks. Contributions come out first — tax- and penalty-free at any age. Then conversions, oldest first, each carrying its own five-year clock: inside that window and before 59½ they carry the 10% penalty but no income tax, since they were already taxed at conversion. Then earnings, tax-free only once the account is qualified. That means we can compute a Roth conversion ladder, not merely describe one. Note the distinction most tools miss: the penalty depends on age alone, while the five-year clock decides whether earnings are tax-free.

Custodial accounts are treated by ownership, not by label. A UTMA is an irrevocable gift— legally the child’s from the moment it is funded — so it is excluded from the assets we count as available to fund your retirement, and it leaves your balance sheet at the age of majority. A 529 stays yours: you remain the account owner and can change the beneficiary.

Two details that are often modelled wrongly and that we handle explicitly: interest on cash is ordinary income taxed in every year, not only in retirement; and a pension is 100% taxable, unlike Social Security, which is taxable only in part. A pension also counts as other income when determining how much of your Social Security benefit becomes taxable, so it raises tax twice over.

Rental propertyis modelled for any number of properties, and the whole point is that a rental’s cash flow and its taxable income are different numbers— routinely with opposite signs. Depreciation is a deduction that costs no cash; mortgage principal is cash that isn’t deductible. So a property can pay you and report a loss in the same year, and we report both figures rather than forcing one to stand for the other. We take 27.5-year straight-line depreciation on the building only (land never depreciates), apply the passive-loss rules — up to $25,000 against other income, phasing out between $100,000 and $150,000 of MAGI, with anything disallowed suspended and carried forward rather than lost — and treat that allowance as a household limit, so four properties don’t get four allowances. On a sale we charge depreciation recapture at 25% on every deduction taken, plus capital gains on the appreciation above it. That last part surprises people: your mortgage is repaid out of the proceeds but doesn’t reduce the gain, so a heavily financed property can owe more tax than the sale hands over in cash.

One-time windfalls — an inheritance, a bonus, selling equity — are modelled, and where the money comes from decides the tax. This is the part that is worth being careful about, because the range is the whole range: the same $200,000 costs you nothing if you inherit it (an inheritance isn’t taxable income to you, and it arrives with a stepped-up cost basis) and tens of thousands if it’s a bonus, which is ordinary wages and owes payroll tax on top. Selling equity is taxed only on the gain above what you paid. A legal settlement genuinely varies — compensation for physical injury is excluded, punitive damages and lost wages are not — so we ask you for the taxable share rather than inventing one. There is no single “windfall tax rate”, and any tool that implies otherwise is guessing.

Read the full tax FAQ ↓ — withdrawal order, the 0% capital gains band, required minimum distributions, Social Security taxability, and an explicit list of what we do not model.

5. Monte-Carlo risk (sequence of returns)

A single average return hides the biggest retirement risk: a bad market early in retirement. Rightmont runs many randomized return paths around the 7.0% average and reports the share that keep your plan funded. You get a probability of success, not a false promise. That’s what separates a plan that survives a 2008-style start from one that only works on paper.

6. What we do NOT model (on purpose)

Being trustworthy means being clear about the edges. Rightmont doesn’t currently model: sub-annual (monthly) detail, per-category inflation, health-shock or job-loss events (model these as a lower income or a one-off expense), AMT or full state-specific brackets, dynamic “guardrail” withdrawal strategies in the base projection, or estate/gift tax. We’d rather say so than imply a precision we don’t have.

On windfalls, we don’t model estate tax or gift tax — both are the estate’s or the giver’s liability and are settled before you see the money, so what you enter is already net of them. We also don’t model the carryover basis a gift actually keeps (we credit basis at the amount received, which understates a later gain), capital-loss carryforwards, or the inheritance taxes several states levy even though the federal system does not.

On rental property specifically, we don’t model the QBI/§199A deduction a rental may qualify for, 1031 like-kind exchanges, short-term and vacation-rental treatment with its material-participation tests, or cost segregation and bonus depreciation. Every one of those would either reduce your tax or change when you pay it, so leaving them out errs the same way the rest of the engine does — conservative, and stated rather than hidden. The 3.8% net investment income tax IS modelled, and rental income counts toward it unless you tell us you are a real estate professional.

7. Our accuracy commitment

Every number Rightmont publishes (on a plan, a scenario page, or in the chat) traces to this engine or to the constants above. Content is checked for arithmetic, framing, and claim accuracy before it ships, and re-checked over time. If a figure can’t be defended, we don’t publish it.

The government figures behind these numbers — the Medicare Part B premium, the full IRMAA brackets and the federal poverty guidelines — are published with their primary sources and verification dates in our reference database. Free to use and cite.

Tax FAQ

How Rightmont handles tax, in detail — including what it does not model.

How tax is calculated

How does Rightmont calculate my taxes?+

Taxes are recalculated every projected year, not estimated once. Each year we apply the current progressive federal brackets to your income after the standard deduction ($32,200 married filing jointly), a state income tax rate you can set, FICA on wages including the 0.9% Additional Medicare surtax above the threshold, bracketed long-term capital gains on taxable investment sales, and the IRS provisional-income worksheet to determine how much of your Social Security is taxable. The same calculation runs behind every page, so the tax figure on a scenario page and the one in your plan come from the same source. These are modeled projections using current law, not tax advice.

What is the difference between my effective and marginal tax rate?+

Your marginal rate is what the next dollar you earn would be taxed at. Your effective rate is total tax divided by total income, and it is always lower, because the earlier dollars were taxed in lower brackets. A common mistake is applying the marginal rate to all income — that overstates tax substantially. Rightmont reports both per year, and applies the bracket-by-bracket calculation rather than a single rate.

Does a raise that moves me into a higher bracket cost me money?+

No. Only the income above the bracket threshold is taxed at the higher rate — the income below it stays taxed at the lower rates. Moving into a higher bracket never reduces your take-home pay. (Benefit cliffs, which are a different mechanism, genuinely can; those depend on programs Rightmont does not model.)

Does Rightmont model state taxes?+

Partly, and it is important to know the limit. We apply one flat state income tax rate that you set, defaulting to 5%. We do NOT model progressive state brackets, and we do not model state-specific retirement income exclusions. Because most states do not tax Social Security and many exempt some pension or retirement income, a single flat rate tends to OVERSTATE tax in retirement for most households. Treat the state portion as an approximation, not a filing figure.

Is the interest on my savings taxed?+

Yes. Interest on cash and high-yield savings is ordinary income, taxed at your regular federal rate in every year you earn it — while you are working as well as in retirement. It is not deferred and it does not get the lower long-term capital gains rates. This is one reason holding a very large cash balance is expensive: it earns less than invested assets and is taxed at a higher rate on what it does earn. Rightmont's default is to hold a set number of months of expenses in cash and invest the rest, with that target recalculated each year from your actual expenses so it keeps pace as your costs rise.

Capital gains

How are capital gains taxed in my projection?+

Long-term capital gains are taxed at 0%, 15%, or 20% depending on your taxable income — not a flat rate. Gains stack on top of your ordinary income, exactly as the real calculation works: your ordinary income fills the brackets first, then gains are layered above it. Married filing jointly, the 0% band runs to $98,900 of taxable income and the 20% rate begins above $613,700. Filing single, the 0% band runs to $49,450. We also track your cost basis, so only the gain portion of a withdrawal is taxed, not the whole amount.

What is the 0% capital gains bracket?+

If your taxable income is low enough, long-term capital gains are taxed at 0% federally. Married filing jointly, that band covers taxable income up to $98,900. This is one of the largest levers an early retiree has: in years between leaving work and starting Social Security or required distributions, income is often low enough that a meaningful amount of gains can be realized at zero federal tax. Rightmont computes gains at the bracketed rate rather than a flat one, so a projection reflects the 0% band where it genuinely applies. Note that Roth conversions and gain harvesting compete for the same bracket space — using it for one means it is not available for the other.

Does Rightmont model tax-loss harvesting?+

No. We model gains and cost basis, but we do not model harvesting losses to offset them, and we do not model the wash-sale rule. Projections therefore do not include any benefit from a loss-harvesting strategy.

Retirement withdrawals

Which accounts does Rightmont withdraw from first in retirement?+

By default, the conventional order: cash and high-yield savings first, then taxable brokerage, then pre-tax 401(k) and Traditional IRA, then Roth last. This is the order taught most widely, and it keeps tax-advantaged accounts compounding longest. You can switch to a tax-optimizing order in Assumptions, which withdraws from pre-tax accounts up to the top of a target bracket (12% by default) before selling taxable assets.

Why would I withdraw from a pre-tax account before a taxable one?+

Because strictly deferring pre-tax withdrawals lets that balance compound until required minimum distributions force large withdrawals from age 73 — often taxed at a HIGHER rate than you would have paid earlier. Deliberately withdrawing up to the top of a low bracket in low-income years levels your lifetime marginal rate and shrinks those future required distributions. The trade-off is real and it is not free: you pay some tax sooner, and in a year where your gains would have fallen in the 0% capital gains band, filling an ordinary bracket instead costs money up front. That is why Rightmont defaults to the conventional order and makes this a choice, and why each year states what it did and why.

Can I take money out of a Roth before 59½?+

Your contributions, yes — at any age, for any reason, with no tax and no penalty. A Roth is not one pot: the IRS ordering rules take your own contributions out first, and only once those are exhausted do you reach earnings, which before 59½ are taxed as ordinary income and hit with a 10% penalty. This is what makes a Roth usable as an early-retirement bridge, and it is the mechanism behind the Roth conversion ladder. Rightmont applies these ordering rules, so it will not penalise a withdrawal that comes out of contributions — but it needs to know your contribution basis. If you leave that at zero we treat the whole balance as earnings, which OVERSTATES the penalty.

Does Rightmont model the Roth five-year rules and the conversion ladder?+

Yes — both clocks, which are separate rules that are often confused. The first is a single clock running from your FIRST contribution to any Roth; until five years have passed, earnings are taxable even after 59½. The second applies to each CONVERSION individually: money you converted carries its own five-year clock, and withdrawing it inside that window before 59½ triggers the 10% penalty — though no income tax, because it was already taxed when you converted. Once the clock matures, or once you pass 59½, it comes out free. That is the Roth conversion ladder, and Rightmont computes it rather than just describing it: enter your prior conversions and it will show which are seasoned. One distinction worth holding onto: the 10% penalty depends on your AGE alone, while the five-year clock decides whether earnings are TAX-FREE. Someone aged 65 whose first Roth is two years old owes income tax on earnings but no penalty.

How much does health insurance cost if I retire before 65?+

More than almost anyone budgets for, which is why Rightmont models it as its own line rather than burying it in your spending. Retiring before 65 means no employer plan and no Medicare, so you buy your own coverage at full price until Medicare begins. That gap is usually the most expensive healthcare of your life, and it lands in the years your portfolio can least afford it. Rightmont models three stages — your share of an employer premium while working, a marketplace plan through the gap, and Medicare from 65 — and inflates them at a healthcare rate you set ABOVE general inflation, because medical costs have persistently risen faster than the general price level.

How does the ACA subsidy work, and what is the 400% cliff?+

The premium tax credit caps what you pay for a benchmark marketplace plan at a share of your income. That share rises with income, so the credit shrinks as you earn more — and it is measured against the federal poverty level for your household size, so a family of four qualifies at a much higher income than a single person. Above 400% of the poverty level the credit does not taper: it disappears entirely. That is the cliff, and it means one extra dollar of income can cost you an entire year's credit. The enhanced subsidies that removed the cliff expired at the end of 2025, so Rightmont models current law with the cliff in place, and lets you model an extension instead — because whether Congress restores them is a policy question we should not answer for you.

Can a Roth conversion or 401(k) withdrawal cost me my health subsidy?+

Yes, and this is the trap that catches early retirees. Money you pull from a pre-tax account is income, income raises your MAGI, and MAGI is exactly what the subsidy is measured against. Near the 400% cliff a modest withdrawal can forfeit the entire credit — an effective marginal cost far above any tax bracket. Rightmont's tax-optimizing withdrawal strategy accounts for this directly: before it fills a low bracket it prices the subsidy that withdrawal would destroy, and declines when the credit is worth more than the tax saved. Without that check a plan can report a tax saving while quietly losing money. The subsidy is also reconciled at year end against your actual income, the way Form 8962 does, so an excess advance credit is repaid rather than silently kept.

What are the limits of the healthcare modeling?+

One thing worth knowing: below 100% of the poverty level we show no premium credit at all; most states would offer Medicaid instead, so that case is deliberately conservative and overstates your cost. We also interpolate the schedule that sets your expected contribution rather than using the published bracketed table — close, but not exact. Premium figures are estimates you should replace with real quotes for your state, age and plan.

What is IRMAA, and why does it surprise so many retirees?+

IRMAA is a surcharge on Medicare Part B and Part D premiums for higher incomes, and what makes it a trap is the timing: it is set from the income on your tax return from TWO YEARS earlier. A Roth conversion at 63 raises your Medicare premium at 65, long after the decision can be undone. It is also a cliff at every tier rather than a taper — one dollar over a threshold raises your premium for the whole year. Rightmont models it from the published Social Security tables with the real two-year lookback, so you can see a surcharge coming before you trigger it rather than after.

Does Rightmont model an HSA, and how is the triple tax advantage handled?+

Yes — all three legs of the triple tax advantage. The contribution is deducted above the line, so it reduces your taxable income the same way a pre-tax 401(k) does; the growth is never taxed; and a qualified medical withdrawal is never taxed either. Contributions are capped at the IRS limit for your coverage — self-only or family — with the extra catch-up amount from age 55, and anything you enter above the limit is reduced to it rather than accepted. Contributions stop at retirement, because enrolling in Medicare ends HSA eligibility.

Why is an HSA worth more than a 401(k) dollar for dollar?+

Because of a fourth advantage that gets far less attention than the triple one: if you contribute through PAYROLL, the money escapes Social Security and Medicare tax as well as income tax. No 401(k), IRA or Roth does that. Below the Social Security wage base that is worth an extra 7.65% on top of the income-tax deduction. Above it, Social Security has already stopped, so the saving falls to the Medicare portion — which is why Rightmont computes the exact amount for your income instead of applying a flat rate, and shows it as "HSA Tax Saved" on the tax schedule. Contribute directly instead of through payroll and you still get the income-tax deduction, but you owe the FICA.

Should my HSA be spent on medical costs or treated as a retirement account?+

Both are legitimate, and Rightmont asks rather than assuming, because the choice changes your projection substantially. Treat it as a MEDICAL RESERVE and we hold the balance aside: it keeps compounding, it never funds general spending, and it carries no future tax bill, because qualified medical withdrawals are untaxed. Treat it as RETIREMENT SPENDING — sometimes called the "super-IRA" approach — and from age 65 it can fund anything, taxed as ordinary income with no penalty, exactly like a Traditional IRA; we then show the deferred tax it owes on your balance sheet. The reserve looks better on paper precisely because it assumes you have healthcare costs to spend it on, so choose the one that matches what you actually intend to do.

Can I take money out of an HSA before 65?+

You can, but for a non-medical purpose it is the most expensive money you own: ordinary income tax PLUS a 20% penalty, double the 10% a 401(k) charges before 59½. Rightmont therefore never draws from an HSA before 65 to cover general spending in either mode — there is always a cheaper source, so modelling it would imply we recommend it. From 65 the penalty disappears entirely and only ordinary income tax remains. Reimbursing yourself for qualified medical expenses is untaxed at any age, and there is no deadline on doing so, though Rightmont does not model receipt-shoeboxing.

How are required minimum distributions handled?+

Required minimum distributions begin at age 73, following the SECURE 2.0 Act, and are computed from your pre-tax balance using the IRS Uniform Lifetime Table divisors. They are taxed as ordinary income and are forced whether or not you need the money, which is why they can push a retiree into a higher bracket than they were in while working.

How much of my Social Security will be taxed?+

Between 0% and 85% of your benefit, depending on your other income. We apply the full IRC Section 86 worksheet rather than assuming a flat share: we compute provisional income (other taxable income plus half your benefit), compare it against the two thresholds, and cap the taxable portion at 50% or 85% accordingly. Many tools simply assume 85% is taxable, which overstates tax for lower-income retirees.

Is my pension taxed the same way as Social Security?+

No, and the difference matters. A pension is 100% taxable as ordinary income. Social Security is taxable only in part — between 0% and 85% of the benefit, depending on your other income under the IRC Section 86 worksheet. Rightmont reports them separately and taxes them differently. Your pension also counts as "other income" when determining how much of your Social Security becomes taxable, so a larger pension raises your tax twice over: once on the pension itself, and again by pushing more of your benefit into taxability. State treatment varies widely and we do not model it — many states exempt some or all pension income, so the state portion of a retiree's projection is likely to be overstated.

What happens if I withdraw from retirement accounts early?+

Withdrawals from pre-tax retirement accounts before age 59½ are generally taxed as ordinary income plus a 10% early-withdrawal penalty, and Rightmont applies that penalty (approximated at age 60) when a projection requires an early withdrawal. We do NOT model the penalty-free exceptions — the Rule of 55 or SEPP/72(t) substantially equal periodic payments — so an early-retirement projection may show more penalty cost than a household using those routes would actually pay. The tax-optimizing withdrawal order never chooses an early withdrawal, since paying a 10% penalty to save a lower rate would be counterproductive.

Limits and what we don’t model

Are contribution limits and catch-up contributions current?+

Yes. We enforce the current IRS elective deferral limit ($24,500 for those under 50), the age-50 catch-up ($32,500 total), and the SECURE 2.0 enhanced catch-up for ages 60 through 63 ($35,750 total). If your inputs would exceed a limit, the projection caps the contribution rather than silently modeling an impossible one.

What tax situations does Rightmont NOT model?+

We publish this deliberately. Not modeled: rental property income and depreciation, the Net Investment Income Tax, the Alternative Minimum Tax, itemized deductions (we use the standard deduction), qualified charitable distributions, tax-loss harvesting, the Rule of 55 and SEPP, progressive state brackets, and state retirement-income exclusions. RSU vesting IS modeled — ordinary income at vest, capital gains from the vest-date basis on a later sale — but 83(b) elections, stock options (ISO/NQSO) and the AMT they can trigger, and ESPP discounts are not. If a strategy on that list matters to your situation, treat the projection as a baseline and consult a tax professional.

Is this tax advice?+

No. Rightmont models federal tax mechanics and a blended state rate to project outcomes under current law. It is not tax, legal, or investment advice, individual situations vary, and tax law changes. Use it to compare decisions and understand the shape of a trade-off, not to prepare a return or make a filing decision.

For educational purposes only, not financial advice.