What Can You Actually Afford to Protect?

Gross, net and discretionary: three numbers people keep confusing

Most budgets fail on arithmetic before they fail on discipline, because the income figure at the top is the wrong one. Gross, net and discretionary describe three different amounts, and only the third is the money a plan can actually move.

Gross income

Your pay before anything is removed. It is the number on the offer letter, on the loan application, and in almost every conversation about salary. It is also the number you never see. Lenders use it deliberately: the Consumer Financial Protection Bureau defines the debt-to-income ratio as “all your monthly debt payments divided by your gross monthly income”, which is why the payment a lender approves can be one you cannot comfortably make.

Net, or take-home, pay

What lands in the account. Gross minus federal and state withholding, Social Security and Medicare tax, and payroll deductions: retirement contributions, your share of the health premium, HSA or FSA money, disability cover, dues. Two people with identical salaries can take home very different amounts, and a 401(k) contribution is a savings decision that has already been made before the deposit arrives. Enter take-home in this calculator, and do not enter payroll retirement contributions again as a savings transfer.

Discretionary income

Take-home minus essentials minus existing commitments. It is the only figure that answers what you could start or stop doing this month. Be careful with the term outside a budget: federal income-driven student loan repayment plans and some benefit programs define discretionary income by their own statutory formula tied to the federal poverty guideline, so the number on a repayment notice will not match the one here and is not meant to.

Fixed, variable and periodic expenses

Expenses behave in three different ways, and a budget that treats them all as one monthly number is wrong twice a year. Sorting them by behaviour, not by category, is what makes the total hold up.

Fixed

Same amount, same date: rent or mortgage, car payment, insurance premiums, childcare, debt minimums, subscriptions. Easy to record and hard to change quickly, which is why the fixed block sets the floor under everything else. A household whose fixed costs already exceed take-home pay cannot budget its way out inside a month.

Variable

Recurs every month, different size each time: groceries, fuel, utilities, medical copays, repairs. These are where a budget is usually wrong, because people enter a good month. Pull three months of statements and use the highest, not the average — a variable expense budgeted at its best month is a shortfall waiting to happen.

Periodic: the annual bills that wreck budgets

Real, predictable, and absent from eleven monthly budgets out of twelve. Auto insurance paid every six months. Vehicle registration and inspection. HOA assessments. Tax preparation. Professional licences and dues. Holidays, birthdays, back-to-school, camps, the annual vet visit. None of them is a surprise, yet all of them arrive as one, because a monthly budget has nowhere to put them. The fix is arithmetic, not willpower: total each one for the year, divide by twelve, and hold that amount in a separate account. The calculator above has a dedicated section for yearly totals and spreads them across the month for you.

What belongs in each category, and whether it is essential

The line between essential and discretionary is where most budgets get argued about, so it is worth being explicit. Essential here means the bill continues whether or not you engage with it, and skipping it has a consequence beyond inconvenience. Discretionary means you could stop it inside one billing cycle without losing the house, the car, or your health cover.

For a sense of scale, the Bureau of Labor Statistics Consumer Expenditure Survey put average annual expenditures per consumer unit at $78,535 for 2024, of which housing was $26,266 (33.4%), transportation $13,318 (17.0%), food $10,169 (12.9%) and healthcare $6,197 (7.9%), against average income before taxes of $104,207 (BLS Consumer Expenditures — 2024). Those are national averages across every household size and income level, so they are a reference point, not a target.

The 50/30/20 rule, and where it breaks down

The 50/30/20 rule splits after-tax income into 50% needs, 30% wants and 20% savings. It was popularised by Elizabeth Warren and Amelia Warren Tyagi in All Your Worth (2005). Its value is that it is memorable and forces savings into the plan from the start rather than treating it as whatever survives the month. It is a rule of thumb, not a standard: no agency publishes it, no lender applies it, and it has no adjustment for household size, local costs, or income.

Where it breaks at lower incomes

Needs are not proportional to income. Rent, a car, groceries and childcare cost roughly what they cost, so as income falls their share rises. A household where housing alone takes 40% of take-home pay cannot reach 50% needs by budgeting, and being told to hit 20% savings while the needs bucket is at 75% is not useful information. The honest reading of a needs-heavy split is a cost-structure problem, and it is usually solved by changing one large fixed cost — housing or transportation — not by trimming the small ones.

Where it breaks at higher incomes

The rule caps ambition at the top. A household whose needs genuinely run at 30% of take-home pay has no reason to spend 30% on wants and save only 20%; the rule would licence lifestyle inflation that a 40% savings rate would otherwise have prevented. High earners also hit a definitional problem the rule ignores: for someone with substantial payroll deductions, a large share of saving already happened before take-home pay was calculated, so the 20% is measured against a base that already had savings removed from it. Read the comparison in the calculator as a diagnostic of your cost structure, not a score.

How to size an emergency fund

Size it against essential monthly outgo, not against income and not against total spending. If income stopped, discretionary spending would stop with it; what continues is housing, utilities, transport, food, insurance premiums and debt minimums. That figure is the burn rate, and the calculator uses it for both the runway and the three- and six-month targets.

There is no official number. The CFPB’s guide to building an emergency fund declines to prescribe an amount, advising instead that you consider the most common unexpected expenses you have actually had and what they cost, and noting that even a small amount provides some security. Three and six months are conventions worth knowing, not rules. Adjust for how replaceable your income is: two salaried earners in different industries carry less income risk than one earner on commission, and a household with a high fixed-cost floor needs more months than one that could cut deeply in a crisis.

Keep it somewhere boring and reachable — a separate savings or money market account at an insured institution, not the account the debit card draws from and not somewhere a market can be down on the day you need it. If you are choosing between building the fund and clearing a high-rate balance, the debt payoff calculator shows what the interest is actually costing you per month, which is the number that settles the argument.

How to budget irregular or 1099 income

Budget from a floor, not an average. Take the lowest month of the past twelve — or the average of the three worst — and build the essential budget on that. Everything above the floor is variable income to be assigned when it arrives, not spent in advance. In a strong month the surplus does three jobs in order: refills the buffer the weak months drained, funds the annual and periodic bills, then goes to savings or debt.

Two amounts have to come off the top before any of that, because nobody withholds them for you. Self-employment tax is 15.3% of net earnings, made up of 12.4% for Social Security and 2.9% for Medicare, and it applies once net earnings from self-employment reach $400. Income tax is separate, and the IRS requires estimated tax payments in four periods across the year from individuals who expect to owe $1,000 or more when the return is filed. Move a fixed percentage into a separate account the day money arrives and treat that account as somebody else’s. What you enter as take-home pay in this calculator should be what is left after that transfer.

Commission and bonus income follows the same logic. Budget the base, treat the variable part as unscheduled, and decide its job before it lands.

What the affordability guide does and does not do

The last panel in the calculator takes a percentage you choose and shows what it comes to in dollars, against two different bases: your unallocated surplus, and your discretionary income. It is deliberately not a recommendation. It names no product, suggests no coverage amount, and does not imply that committing anything is the right move.

The reason both bases are shown is that the difference between them is the whole point. Surplus is money that currently has no job, so committing part of it changes nothing else in the budget. Discretionary income still has your lifestyle spending inside it, so committing a share of that means something in the wants column has to shrink. A fixed monthly premium is a commitment that behaves like a bill: it is easy to start and awkward to stop, and it should be sized against money that will still be there in a thin month.

What no calculator can supply is the other half of the question — who depends on your income, what would still need paying if it stopped, what coverage already exists, and what any of it would actually cost you at your age and health. Cash flow tells you what is available. It cannot tell you what is needed.

Where this fits with the other calculators

This is a cash flow tool: it measures money moving through a month. Two related questions need different tools, and using the wrong one is a common source of confusion.

• Financial Inventory Calculator — the balance sheet. What you own and what you owe at a single moment: net worth, liquidity, and how your investment balances split across tax treatment. Balances, not flows. A household can have a strong balance sheet and negative cash flow, or the reverse.
• Debt Payoff Calculator — what to do with the surplus this page finds, if debt is where it should go. It models payoff order and the interest saved.

The natural order is this page first, the inventory second. Cash flow tells you what you can commit; the balance sheet tells you what would happen if you stopped being able to.

How this calculator works

Every output is arithmetic you can check by hand. Nothing is projected, no growth rate is applied, and no assumption is made about anything you did not type.

Frequently asked questions

Assumptions, limitations and disclaimer

• The calculator uses only the figures you enter. It applies no inflation adjustment, no growth rate, and no tax calculation, and it does not project anything forward.
• It does not compute your withholding. If you enter a gross figure it is used for one comparison only; take-home pay must come from your own pay statement.
• Where a category is essential and where it is discretionary is a judgement, and this page applies one consistent set. A different classification produces a different 50/30/20 split.
• 50/30/20 is a rule of thumb from a 2005 book, not a regulation, a lending standard, or a benchmark published by any agency. The comparison describes a gap; it does not grade you.
• Three and six months of expenses are common reference points for an emergency fund, not official targets. The CFPB does not publish an amount.
• The affordability panel converts a percentage you choose into dollars. It is not a recommendation, not a suitability assessment, and not a quote. It does not name a product or suggest a coverage amount, because it cannot know your goals, your dependants, or your health.
• BLS figures quoted above are national averages for the 2024 reference year across all household sizes and income levels. They describe the population, not you.
• The page opens with example figures for illustration. They are not typical, recommended, or benchmark values.

This is an estimate, not advice. The results above are an informational illustration based on figures you supplied. They are not a quote, not an offer of insurance, and not a substitute for advice from a qualified professional about your own situation.