Question 1

The 50/30/20 rule

Accepted Answer

A simple budgeting framework: spend ~50% of after-tax income on needs (rent, utilities, groceries, transport), 30% on wants (dining, subscriptions, hobbies), and put 20% toward savings, investments, and debt repayment. It's not gospel — adjust the percentages to your situation.

Question 2

Tip: pipe leftover into investing

Accepted Answer

When your "Leftover" is positive, the KPI shows a "Use in" button that pipes the amount into the Compound Interest or Retirement Planner as your monthly contribution — instant projection of what consistent saving turns into.

Question 3

Detailed view vs. rule view

Accepted Answer

Detailed view lists every income source and expense line by line — best for finding leaks ("how much actually goes on subscriptions?"). Rule view collapses everything into the three 50 / 30 / 20 buckets and shows colour-coded bars for actual vs. target — best for high-level course correction. Switch between them at the top of the calculator.

Question 4

When 50 / 30 / 20 doesn't fit

Accepted Answer

The rule was popularised by Senator Elizabeth Warren as an approachable starting point for middle-class US households. It doesn't fit aggressive savers (who push 20 → 40+%), people in expensive cities where rent alone eats 50% of net (no flex left for "wants"), or people in active debt-payoff modes. Treat it as a sanity check, not a contract.

Question 5

Common mistakes

Accepted Answer

Two patterns kill the usefulness of a budget: (1) using your gross salary instead of net (post-tax) — you can't spend money you don't see; (2) forgetting irregular expenses (annual insurance premiums, holiday gifts, vehicle service). Add them as monthly averages — divide an annual figure by 12 — so they don't ambush your January.

月度預算規劃 — 50/30/20 法則

50/30/20 法則

小撇步：把結餘導入投資

詳細檢視 vs. 法則檢視

50/30/20 不適用的時候

常見誤區

不做的事