Discretionary income is the money you have left after paying taxes and covering necessary living expenses like housing, food, utilities, transportation, insurance, and minimum debt payments. It’s the cash you can actually choose how to spend — on savings, investing, or anything non-essential. The definition of discretionary income also has a precise legal meaning in federal student loan repayment and in bankruptcy, where standardized formulas replace personal judgment about what counts as necessary.
Discretionary Income vs. Disposable Income
These terms often get used interchangeably, but they measure different things. Disposable income is your take-home pay: gross earnings minus mandatory deductions like federal and state income taxes, Social Security, and Medicare. If your paycheck shows $4,500 after withholdings, that’s your disposable income.
Discretionary income goes one step further. It takes disposable income and subtracts necessary living expenses — rent or mortgage, groceries, utilities, basic transportation, insurance, and minimum debt payments. What remains is what you can genuinely choose how to spend.
The difference can flip who has more financial freedom. Someone with $7,000 in monthly disposable income and $5,500 in necessary expenses has only $1,500 in discretionary income. Someone earning $4,000 in disposable income but with just $2,000 in necessary costs has $2,000 in discretionary income, despite the smaller paycheck.
How to Calculate Discretionary Income
The general formula: start with gross income, subtract mandatory tax deductions to get disposable income, then subtract necessary living expenses. The second subtraction is where things get subjective, because people reasonably disagree about what counts as necessary.
Here’s a worked example for someone earning $72,000 a year, or $6,000 monthly gross:
- Gross monthly income: $6,000
- Taxes and mandatory deductions: −$1,500 (federal and state income tax, Social Security, Medicare)
- Disposable income: $4,500
- Necessary expenses: −$2,900 (rent $1,400, utilities $250, groceries $400, health insurance $300, minimum debt payments $350, transportation $200)
- Discretionary income: $1,600
That $1,600 is what’s available for dining out, entertainment, extra retirement contributions, or building an emergency fund. If the number comes out negative, basic costs are already exceeding income — a signal that either earnings or the cost structure needs to change.
Court-Ordered Payments
Child support and alimony create a gray area. They’re mandatory in the sense that nonpayment carries legal consequences, which puts them near taxes in terms of obligation. Most financial planners treat them as non-discretionary for personal budgeting. For federal student loan purposes, what matters is whether the payment reduces your adjusted gross income on your tax return. Child support never does. Alimony under agreements executed after 2018 doesn’t either, because it’s no longer tax-deductible for the payer.1Internal Revenue Service. Alimony and Separate Maintenance
Pre-Tax Contributions
Traditional 401(k) and HSA contributions come out of your paycheck before taxes, lowering your adjusted gross income. For personal budgeting, these are technically a choice; you could stop tomorrow. But for any calculation that uses AGI as its starting point, pre-tax contributions directly reduce the income figure that feeds into the formula. The 2026 employee contribution limit for a 401(k) is $24,500, and the IRA limit is $7,500.2Internal Revenue Service. 401(k) Limit Increases to $24,500 for 2026, IRA Limit Increases to $7,500 Roth contributions don’t reduce AGI, because they’re made with after-tax dollars.
What Counts as a Necessary Expense
For personal budgeting, you draw the line yourself. When a government agency or court has to define “necessary,” it uses standardized benchmarks. The IRS publishes National Standards and Local Standards that set allowable amounts for food, clothing, housing, utilities, and transportation based on household size and geographic location.3Internal Revenue Service. Collection Financial Standards
Under IRS collection standards, you’re generally allowed the amount you actually spend or the local standard, whichever is lower. The national food allowance for a single person is $497 per month; for a four-person household, it’s $1,255.4Internal Revenue Service. National Standards – Food, Clothing and Other Items Housing and utility allowances vary by county.
Expenses that typically fall into the necessary category include:
- Housing: rent or mortgage payments, property taxes, insurance
- Utilities: electricity, water, heat, garbage collection, basic phone and internet
- Food: reasonable grocery costs for your household size
- Transportation: vehicle maintenance, fuel, or public transit
- Insurance: health insurance, required auto insurance
- Minimum debt payments: the required minimum on existing loans and credit accounts
The line between necessary and discretionary is sometimes obvious and sometimes not. Basic internet is arguably necessary for work; a $200 premium streaming bundle is clearly discretionary. A used sedan to get to work is necessary; a luxury car lease that triples the payment is discretionary spending dressed up as transportation.
The Student Loan Definition
If you have federal student loans, discretionary income has a specific legal meaning that differs from the personal-finance version. Income-driven repayment plans ignore your rent, groceries, and utility bills. Instead, they use a formula tied to the federal poverty guideline.
For Income-Based Repayment (IBR) and Pay As You Earn (PAYE), discretionary income equals your adjusted gross income minus 150% of the federal poverty guideline for your family size.5GovInfo. 20 USC 1098e – Income-Based Repayment For Income-Contingent Repayment (ICR), the threshold is lower: only 100% of the poverty guideline is subtracted.6Consumer Financial Protection Bureau. Data Point – Borrower Experiences on Income-Driven Repayment
The 2026 federal poverty guideline for a single person in the contiguous United States is $15,960.7Federal Register. Annual Update of the HHS Poverty Guidelines For larger households, the guideline increases: $21,640 for two people, $27,320 for three, and $33,000 for four.8U.S. Department of Health and Human Services. 2026 Poverty Guidelines – 48 Contiguous States
A Sample Calculation
A single borrower with an AGI of $45,000 would calculate discretionary income under IBR or PAYE this way:
- 150% of the poverty guideline: $15,960 × 1.5 = $23,940
- Discretionary income: $45,000 − $23,940 = $21,060
The monthly payment is a percentage of that figure. If you first borrowed after July 1, 2014, IBR charges 10%. If you borrowed earlier, it charges 15%. PAYE always charges 10%.9Federal Student Aid. Income-Driven Repayment Plans In this example, a newer IBR borrower would pay about $175 per month ($21,060 × 10% ÷ 12).
Because the formula uses AGI rather than take-home pay, anything that lowers AGI lowers your calculated discretionary income and therefore your payment. Traditional 401(k) contributions, HSA contributions, and above-the-line deductions like student loan interest all reduce AGI. Roth contributions do not. The currently available income-driven plans are IBR, PAYE, and ICR.9Federal Student Aid. Income-Driven Repayment Plans
Discretionary Income in Bankruptcy
Bankruptcy courts also rely on discretionary income, though they don’t use that label. The Chapter 7 means test determines whether a debtor has enough surplus income to repay creditors, which would make a Chapter 7 filing presumptively abusive. The court calculates monthly income, then subtracts allowable expenses drawn directly from the IRS National and Local Standards.10Office of the Law Revision Counsel. 11 USC 707 – Dismissal of a Case or Conversion to a Case Under Chapter 11 or 13
You can’t claim whatever expenses you want. Allowable amounts for food, clothing, housing, and transportation are capped by IRS standards, with housing and utility limits varying by county.11U.S. Department of Justice. IRS National Standards for Allowable Living Expenses The court may allow an additional 5% above the food and clothing standard if the debtor shows it’s reasonable and necessary. Health and disability insurance costs are included. Payments on existing debts generally are not counted as allowable monthly expenses under the means test formula.
If the resulting surplus multiplied by 60 months exceeds certain thresholds, the court presumes you can fund a repayment plan and may push you toward Chapter 13 instead of a Chapter 7 discharge.
Why the Number Matters
Lenders look at discretionary income to gauge whether you can realistically handle another payment. A high disposable income means little if fixed costs eat most of it. The gap between what you earn after taxes and what you must spend to keep the lights on is the truer measure of borrowing capacity.
For personal budgeting, tracking discretionary income over several months reveals patterns that gross income never will. You might earn $80,000 a year and still struggle to save because necessary costs consume nearly everything. Or you might earn $50,000 and save aggressively because your cost structure is lean. What matters for building wealth isn’t what you earn. It’s what’s left after the non-negotiable bills are covered.