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What does coordinating two incomes into one household do to monthly surplus and projected net worth, compared with the same two people running separate households?
Illustrative Monthly take-home figures. Nothing you enter leaves your browser.
| Person A alone | $730 |
| Person B alone | $580 |
| A and B, separate households | $1,310 |
| One combined household | $2,600 |
| What sharing fixed costs is worth per month | $1,290 |
Separate, two households
$214,682
One combined household
$426,086
| Year | Separate invests | Separate balance | Combined invests | Combined balance |
|---|---|---|---|---|
| 1 | $1,310 | $16,160 | $2,600 | $32,072 |
| 2 | $1,310 | $33,316 | $2,600 | $66,123 |
| 3 | $1,310 | $51,530 | $2,600 | $102,274 |
| 4 | $1,310 | $70,868 | $2,600 | $140,654 |
| 5 | $1,310 | $91,399 | $2,600 | $181,402 |
| 6 | $1,310 | $113,196 | $2,600 | $224,663 |
| 7 | $1,310 | $136,337 | $2,600 | $270,592 |
| 8 | $1,310 | $160,905 | $2,600 | $319,354 |
| 9 | $1,310 | $186,989 | $2,600 | $371,124 |
| 10 | $1,310 | $214,682 | $2,600 | $426,086 |
Early on, the savings rate matters more than the return. Here is the combined balance at four rates.
0% a year
$312,000
4% a year
$382,849
6% a year
$426,086
8% a year
$475,660
Each person's monthly surplus is take-home pay minus expenses. The separate case adds the two surpluses; the combined case uses one household's expenses against both incomes. Whatever share of the surplus you choose to invest compounds monthly at the return you set. A raise, if you set one, lifts take-home pay at each year boundary while expenses stay flat. A negative surplus is shown as a shortfall and is not projected. Nothing you enter leaves your browser.
Assumes both incomes continue with no job loss, divorce or caregiving exit; no return volatility; no inflation adjustment. The combined housing number is yours, not a market figure.