The Order of Operations for Money: Where the Next $100 Should Go

You have $100 spare this month, or $1,000, or a bonus. Where should it go? The question generates endless argument online, which is odd, because the underlying logic is simple and nearly everyone's answer lands in the same order.

Every option is an investment with a return. Paying off a card at 24% is an investment returning a guaranteed, tax-free 24%. A pension contribution matched by your employer returns 50% or 100% instantly. A global index fund returns perhaps 5–7% a year above inflation over long periods, with no guarantee in any given year. Cash in a savings account returns whatever the rate is, with certainty.

Rank by return, weight for certainty, and the order writes itself.

0. A one-month buffer in your current account

Before anything else, hold enough in your everyday account that a mistimed direct debit does not trigger an overdraft fee. A few hundred dollars is usually enough. Overdraft and returned-payment charges are among the highest effective interest rates in retail finance — a $30 fee on a $100 shortfall for five days is an annualised rate in the thousands of percent.

1. Any employer pension match

If your employer adds money when you contribute — matching your 4% with 4% of their own, say — that is a 100% return on the day it is paid, before the money is invested in anything.

Nothing else on this list competes. Not a 30% credit card, not anything. If you contribute nothing, you are declining part of your compensation. Contribute at least enough to capture the full match, even while you are in debt, unless the debt is genuinely at crisis level and you cannot make minimum payments.

2. A starter emergency fund of about $1,000

Not the full three-to-six months yet. Just enough that an ordinary mishap — a car repair, a vet bill, a broken phone — does not go on a credit card and undo the work of the next step.

Building the complete fund before touching expensive debt is a mistake commonly made: a 24% card compounds against you the entire time your savings account earns 4%. But going from zero to full attack on debt with no buffer at all is also a mistake, because the first unexpected expense puts you straight back on the card. A small buffer resolves both.

3. Debt above roughly 8%

This is where the interesting comparison happens.

Paying down debt at rate r is a risk-free, tax-free return of r. Investing has a higher expected return, but "expected" is doing a lot of work in that sentence — the actual outcome over any given five-year period ranges from excellent to badly negative.

The 8% threshold is a convention, not a discovery. It sits a little below typical long-run equity returns, which builds in a margin for the fact that those returns are uncertain and the debt interest is not. If you prefer a lower threshold because certainty appeals to you, that is a reasonable preference and not a mistake.

For sequencing several debts at once, see snowball versus avalanche.

4. The full emergency fund

Now build cash reserves properly: three to six months of essential spending, more if your income is volatile or your household depends on a single earner. How big should it be? works through the factors that move that number, and where to keep savings covers the accounts worth using.

Some people prefer to build the full fund before clearing 15% debt. The maths disagrees, but the maths does not have to sleep at night worrying about redundancy. If a larger buffer is what lets you stop thinking about money, the cost of that peace is a few hundred dollars in extra interest — sometimes a fair price.

5. Tax-advantaged long-term investing

With expensive debt gone and cash reserves in place, the priority becomes long-term investing inside whatever tax-sheltered accounts your country offers — pensions and retirement accounts, and tax-free savings or investment accounts where they exist.

The tax shelter is worth more than most people assume, because it compounds. A percentage point of tax drag each year is not a small annual annoyance; over thirty years it is a substantial share of the final balance, in the same way that investment fees are.

What to hold inside those accounts is a separate question, and a simpler one than the industry suggests — see index funds versus ETFs.

6. Everything else

Remaining money goes to whatever fits your goals: taxable investment accounts, overpaying the mortgage, saving for a house deposit, or funding a career change. By this point you are optimising rather than firefighting, and the differences between reasonable choices are small.

Reasonable reasons to deviate

• Job insecurity. If redundancy is a live possibility, cash outranks the maths. Available money buys options; equity in a house or an overpaid loan does not.
• A debt that is wrecking your peace of mind. Clearing a small balance out of order costs little and can be worth a great deal.
• A near-term goal. Money needed within five years generally should not be invested in shares, whatever the expected return, because the timing risk is real.
• Self-employment. Irregular income argues for larger cash reserves earlier in the order.

Common questions