Ch. 01 Deciding
Childcare Costs vs One Income: Running the Numbers
Comparing childcare costs against one income is a real calculation, but almost everyone runs it wrong in the same two ways: they subtract childcare from one salary rather than from household income, and they run it over one month instead of several years. Fix both and the arithmetic gets more honest — and less decisive, because it genuinely favours different answers for different households. This post is about how to set the calculation up. The line-by-line subtraction already lives in what your second income really nets; the point here is what surrounds it.
The comparison most people run, and why it misleads
The standard version: take the childcare quote, put it next to one salary — nearly always the lower-earning parent’s, and in most households that’s the mother’s — and see what’s left. When the answer is “almost nothing”, it feels like the decision has made itself.
Two problems. First, childcare is a household cost that exists because both parents work, so attributing all of it to one salary is a choice, not a fact. Run it the other way and the higher earner’s salary is the one that nets nothing. Second, a single month tells you about the most expensive year of a cost curve that falls, while saying nothing about an earnings line that generally does the opposite.
Neither correction produces a “right” answer. Both stop the maths from quietly deciding for you.
Costs the working column usually leaves out
Add these before you compare anything:
- The commute in full — fuel or transit, parking, and whether a second car exists only because of the job. Insurance and maintenance count too, not just gas.
- The marginal tax rate, not the average one. A second income stacks on top of the first, so it’s taxed at the household’s highest rate rather than at the rate the first dollar sees. That’s the mechanic behind “the second paycheck feels thinner than it looks”. What that rate is for you is a question for a tax professional or the IRS — do not take a number for it off a blog, including this one.
- Employer benefits that only exist while you’re employed. Retirement contributions and any employer match, subsidised health premiums, disability and life cover, paid leave. If your job carries the family’s health insurance, that is not a line item — it’s a structural constraint on the whole decision.
- The offsets that reduce the childcare side. A dependent care FSA through an employer, and the federal child and dependent care credit, both exist to make care cheaper for working parents; the IRS explains eligibility and limits for the credit in Topic no. 602. These shrink the childcare column, so leaving them out biases the comparison towards staying home.
Missing from the staying-home column
The honest version of this post has to run the same exercise in the other direction, and it is the half that gets skipped.
- The earnings path, not just the salary. Leaving costs the salary you can see plus the raises and promotions that would have compounded on top of it, and re-entry frequently starts below where you left. How large that effect is varies enormously by field and by how long you’re out. Nobody should tell you it’s nothing, and nobody honest will tell you exactly what it will be for you.
- Retirement contributions that stop. Years with no earnings are years with no contributions and no match, and they also land on your Social Security earnings record, which is built from your own earnings history — the SSA’s credits and benefit eligibility planner explains how eligibility and benefit amounts are worked out. If the household wants to keep contributing on behalf of a non-earning spouse, that’s a conversation with a fee-only advisor — you can find one through NAPFA — not something to improvise from a comment thread.
- Insurance and risk. Life and disability cover often sits inside employment. On one income, the household’s whole financial position rests on one person’s ability to keep working, which usually means buying cover you previously got for free.
Run it over five years, not one
This is the correction that changes most people’s answer, in both directions. Childcare cost is front-loaded: infant care is typically the most expensive tier, it usually gets cheaper as children move up through preschool rooms, and it falls off a cliff when school starts — after which you’re buying wraparound hours rather than full days. Meanwhile the earnings effect of being out runs the other way: small in year one, larger by year five.
So sketch the years rather than the month:
| Year | Children in paid care | Childcare direction | Earnings-path direction |
|---|---|---|---|
| 1 | Infant, full-time | Highest it will be | Barely affected either way |
| 2 | Toddler room | Slightly lower | Minor |
| 3 | Preschool, possibly plus a second child | Can spike again with a second | Compounding starts to show |
| 4 | Preschool / pre-K | Falling | Meaningful in fast-moving fields |
| 5 | School plus wraparound care | Much lower | Largest of the five years |
Two households with identical salaries can look at that table and honestly reach opposite conclusions — because the expensive years are temporary, and so is the argument for enduring them.
Why the same maths gives different households different answers
Five variables move the answer more than salary does:
How many children, and how far apart. Two under three at once is the peak-cost scenario; spacing them changes the shape completely.
Where you live. Care costs vary widely by region, which is why we point to solomomstrong’s cost-of-daycare data rather than quoting a national average as though it applied to your zip code.
Which job carries the benefits. If insurance, the retirement match and the flexibility all attach to one job, that job is worth more than its salary line implies.
How re-enterable your field is. Licensed and credentialed fields, and fields with formal returnship pipelines, are structurally easier to come back to than fast-moving ones with no re-entry track.
Whether your partner’s schedule can flex. Two rigid schedules make paid care mandatory; one flexible schedule can shrink the hours you buy.
What the number can and can’t tell you
It can tell you whether working is currently costing you money, how long the expensive stretch lasts, and which levers are available — shorter hours, cheaper care arrangements, a delay of a year. It cannot rank two lives against each other, and a spreadsheet that comes out close is telling you something real: at that point the deciding factors are not financial, and pretending otherwise just gives the maths authority it hasn’t earned. The non-financial half of the comparison sits in SAHM vs working mom, and the reversibility question — what it takes to go back later — in what if I regret it.
FAQ: childcare costs versus one income
Is it worth working if childcare costs as much as my salary?
Sometimes yes, sometimes no. If care eats one salary for two or three years but keeps an earnings path, benefits and re-entry intact, plenty of households treat those years as an investment. If the expensive stretch is long, the field is easy to re-enter and the job isn’t one you want, the arithmetic points the other way.
Should childcare be subtracted from one salary or from both?
From household income, if you want the honest version. Assigning it to one parent’s salary is a framing choice that makes the answer look obvious when it isn’t.
What costs do people forget when comparing childcare to a salary?
On the working side: the marginal tax rate, the full commute, and benefits that vanish with the job. On the staying-home side: the earnings path, retirement contributions and the insurance that came free with employment.
Does the child and dependent care credit change the maths much?
It reduces the effective cost of care for eligible working families, so leaving it out overstates the case for staying home. The size depends on your income and expenses — check the IRS guidance or ask a tax professional rather than assuming.
When does childcare stop being the biggest line?
Usually when the youngest child starts school and you switch from paying for full days to paying for wraparound hours. That’s the point most of these comparisons stop being close.
