Cashflow: the tap and the leaks

If you cannot say where last month’s money went, you cannot plan next month’s.

8 min read · Beginner · Updated 2026-09-06

Cashflow is a short sentence: money in, minus money out, equals what is left to protect or grow.

The tap

The tap is income. Salary, stipend, freelance payment, pocket money from home, a side skill that paid this month. Write the number you actually received, not the CTC on the offer letter. CTC includes pieces you never see in the bank.

If income jumps around, use last month’s real credit and a cautious guess for this month. Do not plan on a bonus that has not cleared.

The leaks

Leaks are spends. Some leaks are supposed to exist - rent, food, the metro card. Some leaks are quiet: subscriptions you forgot, UPI to friends that never came back, “just this once” food delivery four times a week.

Split last month into five buckets on paper:

  • Place (rent / hostel)
  • Food
  • Move (commute)
  • People (family transfers, gifts)
  • The rest (everything else)

The fifth bucket is where mystery lives.

A 10-minute audit

Open the bank or UPI history for 30 days. Do not categorise ₹12 tea. Circle the ten largest outflows. Then circle anything that repeats. You now know 80% of the story.

Example. Take-home ₹50,000.

  • Rent ₹18,000
  • Food ₹8,000
  • Commute ₹4,000
  • Family ₹6,000
  • Subscriptions + eating out ₹5,000
  • Mystery UPI ₹3,000
  • Left ₹6,000

Do not start by arguing about every small chai. Start with the big unclear line: what was the ₹3,000 of mystery UPI? And be honest about family ₹6,000: is that a promise you mean to keep every month, or a surprise that keeps breaking the plan?

Net cashflow in one line

Income − spend = raw material.

If that line is near zero every month, there is nothing for the emergency bucket or a SIP. Investing tutorials will not fix a leak. Fixing the leak is the tutorial.

**Note:** Track categories for thirty days, then only the leaks that matter. Tracking every ₹5 forever is how people quit.

Where it breaks

Shame is a bad instrument. A messy month is data. Irregular earners should track a “low month” and a “normal month,” not an average that never happens.

Family cash that goes out in an envelope still counts. If you pretend it does not exist, the audit is fiction.

  • Income minus spend is the only raw material of investing.
  • Mystery spends are usually small and frequent.
  • You cannot invest a leak.

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Key takeaways

  • Income minus spend is the only raw material of investing.
  • Mystery spends are usually small and frequent.
  • You cannot invest a leak.

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Educational only — not investment advice. Part of The Money Operating System on Finnass Guides. Prefer hands-on tools? Open Calculators or the FIRE calculator.