The 50/30/20 rule: what it is and how to run it

The three buckets

The 50/30/20 rule, popularised by Elizabeth Warren and Amelia Warren Tyagi in All Your Worth, splits after-tax income three ways:

You can check three numbers in ten seconds. A thirty-line budget takes an evening, which is why most thirty-line budgets go unread by March.

Work out your three numbers

Start from after-tax income, meaning what reaches your account after tax and any payroll deductions. Using gross income inflates all three numbers and puts the savings target out of reach.

On take-home pay of 5,200 a month:

• Needs: 2,600
• Wants: 1,560
• Savings and debt: 1,040

If your income varies, use the average of the last three months, and re-check it once a quarter rather than every month.

Sorting a category into a bucket

The line between a need and a want is what would survive a halved income.

Housing, groceries, the commute, insurance and minimum debt payments all survive. Those are your needs.

A gym membership does not survive, so it is a want, however good it is for you. The same goes for the premium tier of a phone plan, the gap between a basic and an expensive grocery shop, and a car upgrade. Transport is the need; the extra is a want.

Two cases catch people out:

• Minimum debt payments are a need. Extra repayment is savings. The minimum is contractual; the surplus is a choice to build net worth, and it belongs in the 20%.
• Groceries are a need; delivery fees are a want. If splitting them gets fiddly, put the whole thing in needs and accept the small error. Precision here costs you a decision at every checkout and buys little.

Running it as three budgets

Skip the spreadsheet and use three budget lines.

In Chillar's, create three budgets and scope each to a set of categories: one covering your needs categories with a limit of 50%, one covering wants at 30%, and treat the 20% as the residual you check at month end. Each budget shows the amount spent inside its own period and what is left, computed from your real transactions.

Because the buckets are coarse, you can move a category between them without rebuilding anything. Your first sort will be a little wrong, so that matters.

Where the rule breaks

The 50% needs ceiling assumes housing takes roughly a quarter to a third of take-home pay. Where housing takes half, you cannot reach the ceiling, and no amount of discipline changes that.

The rule earns its keep here. If your needs come to 68%, what is holding you there is location, income or household size, and the moves open to you match: relocate, earn more, or share costs. That is a different conversation from "spend less on coffee", and the rule is what surfaced it.

When needs exceed 50%, hold the 20% savings target fixed and let needs and wants split the remainder. Your savings rate compounds, so protect it, and let the needs-versus-wants boundary flex instead.

What to do next

Work out your three numbers, sort your categories once, and run it for two months without adjusting anything. Then look at which bucket is consistently over and decide whether the limit or the spending was wrong.

For the more precise version, zero-based budgeting assigns every unit of income to a specific category rather than to one of three buckets. It asks more of you, and it shows you more.