Where does it go?
Find the one number that decides everything else: the gap between what comes in and what goes out. Learn to track a month and tell fixed costs from variable ones.
THE ONE NUMBER
The gap
Every month, money comes in and money goes out. Income − spending = the gap. A positive gap is the only raw material you have for a safety buffer, for paying off debt and for investing. A negative gap means the month was paid for with debt or with savings.
Most people know their income to the last cent and their spending only as a feeling. That's why the gap is usually a surprise.
Sara's month
Income (after tax) 3,000
Rent + bills 1,250
Food 600
Transport 250
Everything else 780
----------------------------------
Spending 2,880
Gap = 3,000 - 2,880Gap = +120 a month (4% of income)Sara felt she was saving 'about 500 a month'. The real number only showed up when she added the lines.
Check yourself
Omid earns 5,000 a month and spends 5,150. Mina earns 2,800 and spends 2,500. Who is in the stronger position to build savings right now?
- Omid, because his income is much higher
- Mina, because her gap is positive and his is negative
- Neither: you can't save on under 3,000
- They're equal, since both spend most of what they earn
Show the answer
Mina, because her gap is positive and his is negative
Yes. Mina has +300 to work with every month. Omid is going backwards by 150 a month, whatever his payslip says.
Track one month
- Pick one place to record
A notes app, a spreadsheet or a small notebook. The best tool is the one you'll still be using in week three.
- Write down every payment
Amount and one word for what it was. Card, cash, transfers, subscriptions, the lot. Thirty seconds a day beats an hour of guessing at month end.
- Check against your statements
At the end of the month, compare with your bank and card records to catch what you missed. Automatic payments hide here.
- Group and add up
Six to ten groups is enough: housing, food, transport, bills, health, fun, other. Then work out your gap.
Check yourself
Reza knows his bank balance to the last unit every day of the month. That on its own still can't tell him which group of spending grew the most since last year.
Show the answer
True
True. A balance is one number: what is left. It carries no memory of what the money was spent on, so it can't say whether food, transport or shopping is the group that grew. Only a record by category can, which is why tracking is a separate job from checking.
Two kinds of cost
Fixed
Roughly the same amount every month, and you're committed to it: rent, loan payments, insurance, subscriptions. Hard to change this week. Changing one (moving, renegotiating, cancelling) saves money every month after.
Variable
Changes with your choices day to day: groceries, eating out, taxis, clothes, gifts. Easy to change quickly, but it takes attention each time, and it creeps back when you stop looking.
Check yourself
Fixed or variable?
- Monthly rent
- Dinner out with friends
- Loan instalment
- Taxi rides
- Music streaming subscription
- New shoes
Show the answer
Fixed: Monthly rent, Loan instalment, Music streaming subscription
Variable: Dinner out with friends, Taxi rides, New shoes
Reading your month
- Look at the three biggest groups first. That's where most of the money is, so that's where a change matters.
- Fixed costs above roughly half of income leave little room to move. Note it; don't panic.
- Circle anything you paid for and didn't use or don't remember. Those are the easiest cuts.
- If prices are rising fast, redo the month every few months. Last year's numbers go out of date quickly.
Check yourself
Negar tracked a month and found a gap of −200. Her lease runs another 8 months. She wants the gap at zero by next month. Where should she look first?
- Her largest variable groups, because those can move right away
- Nowhere yet: one month isn't enough data
- Her rent, because it's her biggest single cost and cutting it would close the whole gap
- Her income: a gap this size can only really be closed by earning more
Show the answer
Her largest variable groups, because those can move right away
Right. Rent is locked for now. Eating out, transport and shopping can move this month. The rent question is worth asking when the lease ends.
Check yourself
Match each situation to what it shows
Show the answer
- Spending is higher than income this month → A negative gap
- A gym membership nobody has used since spring → A fixed cost worth cancelling
- Groceries cost 30% more than last year for the same basket → A reason to re-track regularly
- Cash withdrawals with no memory of what they bought → A hole in the record
Lesson recap
- Income − spending = the gap. Everything else in this course is built from a positive gap.
- Track every payment for one month, check it against your statements, then group and add up.
- Fixed costs are slow to change but save every month; variable costs change fast but need attention.
- Start with your biggest groups, and re-track when prices or your life change.