Net worth versus income, and why a high salary isn't wealth

Income is a flow: what comes in over a year. Net worth is a stock: what you have kept, as of today. A high salary that is spent as it arrives leaves net worth flat, and a modest salary with a steady surplus builds it, because net worth grows only by the share of income that is kept, plus whatever the kept money earns. The figure that connects the two is that share, and it is the one number a raise can't change on its own.

A flow and a stock

Think of a bathtub. Income is the tap, spending is the drain, and net worth is the water level. A bigger tap with a bigger drain leaves the level where it was. A small tap with a nearly closed drain fills the tub. The level at any moment says nothing about the size of the tap, and the size of the tap says nothing about the level.

In figures, the change in net worth over a year is income minus spending, plus or minus what the assets you already hold gained or lost. Income minus spending is the part you decide. The rest is the market, and it acts on what you have kept so far, which is why the share kept matters twice: once directly, and again through everything it earns later.

What a high salary buys, and what it doesn't

A high salary buys options: the ability to keep a large share without hardship, to absorb a bad month, and to build net worth quickly if the share kept is held. It doesn't buy wealth on its own. A household with a large income and no surplus is one job loss from trouble, exactly like a household with a small income and no surplus, and the larger fixed costs it has taken on make the trouble arrive faster.

One mechanic makes the point exactly. If you keep a share of income, call it s, then each year of work funds s divided by 1 minus s years of your current spending. At 5% kept, a year of work funds about 19 days. At 20%, three months. At 50%, a full year. The salary sets the size of the numbers; the share sets how many years of freedom each year of work produces.

The number that connects them

1. Add up take-home income for twelve months, every deposit that was yours, plus the income you kept before it reached you: retirement contributions taken from your paycheck and any vested employer match.
2. Add up spending for the same twelve months, including interest, and not including loan principal or the purchase of an asset you track, which are money kept in a different form.
3. Subtract. Income minus spending is what you kept.
4. Divide what you kept by income. That is the share kept, and it is the number to watch from year to year.
5. Check it against the change in net worth. The two should agree once the market's contribution is taken out. If they don't, a balance is stale, an account is missing, or a payroll contribution was left out of step one. See How often to check your net worth for the split.

A worked example

Two households over five years, with the market held flat to isolate the mechanism. Household A takes home $150,000 a year and spends $142,500, keeping 5%. Household B takes home $72,000 and spends $57,600, keeping 20%.

After five years, Household A has kept $37,500, which covers about three months of its spending. Household B has kept $72,000, which covers fifteen months of its spending. The household earning less than half as much has built nearly twice the net worth and almost five times the security, measured in months of expenses. A market return would widen the gap, not close it, because the return applies to what was kept.

If Household A kept 20% instead, it would have $150,000 after five years, and the salary would show. The salary was never the problem. The share was.

Where the salary goes instead

Fixed costs scale with income unless something stops them. Housing, cars, schools, and travel all have a version that costs twice as much, and each raise finds one. The committed share of the month, the bills that are spoken for before anything is decided, tends to stay near the same percentage of income however large the income grows, which is why a household earning $150,000 can feel as tight on the 20th as one earning $72,000. See How much of the month is already spoken for for measuring that share, and How to budget a raise or bonus without lifestyle creep for the moment it gets decided.

Taxes take a larger share of a larger salary too, so the take-home figure grows more slowly than the headline. The number to keep the share against is take-home pay, not the salary in the offer.

Common mistakes

• Judging wealth by income, your own or anyone else's. The salary is the tap, not the level.
• Treating a raise as progress before deciding what share of it is kept.
• Comparing net worth with salary, as in "I earn $150,000 and I'm only worth $40,000". The two are different kinds of number, and the comparison says nothing.
• Measuring saving in dollars rather than share, so that $500 a month looks the same at $50,000 as at $150,000.
• Not noticing that fixed costs scaled up with the last three raises.
• Counting a rise in the home's value as money kept. Both raise net worth; only one was a decision.

Common questions

Is net worth or income the better measure of financial health? The direction of net worth over a year, with the market's contribution taken out. Income measures capacity; net worth measures what was done with it. A high income with a flat net worth is capacity going down the drain.

What share of income is enough to keep? There is no benchmark that fits every household, but the mechanic above gives the trade-off exactly: at 10% kept, each year of work funds about forty days of expenses; at 25%, about four months. The share you keep is the rate at which you buy time.

Can a high earner have a negative net worth? Easily. Student loans from the degree that produced the salary, a mortgage larger than the home's equity in the early years, and two financed cars can add up to more than everything owned, and a large income does nothing about it until a share of it is kept.

Should I count a raise as wealth? No. A raise is a larger flow. It becomes wealth only through the share of it that is kept, and only after that share has been kept for a while.

How does debt fit into the picture? Interest is spending, and it reduces what you keep. Principal payments are money kept, moved from cash to a smaller debt, and they leave net worth unchanged on the day they are made. Paying off a loan raises net worth over time by ending the interest, not by the payments themselves.

How Zypper handles this

Zypper shows the flow and the stock side by side. The cash flow page charts income against spending over any period, which is the take-home part of the share-kept calculation above, done from your categorized transactions with movements between your own accounts left out. To compare its figure with the change in net worth, add back anything the page counted as spending that only changed money's form, such as loan principal or a car bought with cash, and add the retirement contributions withheld from your paycheck, which never pass through a connected account. Net worth is computed from every account, with bank balances, investments, property, and vehicles on the asset side and credit cards and loans on the liability side, and charted over time, so a year of keeping a steady share shows up as a line that rises whatever the salary was. Connected investment and loan accounts contribute their balances, and manual accounts fill in what can't be connected. The budget's Left to budget figure, your expected income minus everything you have budgeted, is the cash surplus you plan for, written down before the month starts. See Cash flow and Net worth tracking for the details, or get started with Zypper to see your own tap and your own level.