Budgeting for a baby on one income: a test you can run first

You are weighing whether one of you will cut back or stop paid work once a baby is part of your life, and every article you open either hands you a stranger's average or tells one family's story that is not yours. There is a third way: instead of guessing, live the budget before you need it. This page walks you through that rehearsal, with a worksheet you can copy and a three-month plan you can start whenever you are ready.

Why a rehearsal beats a spreadsheet guess

A budget on paper is a set of assumptions. It says nothing about the week the car needs repairs, the month you discover how often you really eat out, or how it feels when the second paycheck is missing. A rehearsal swaps those assumptions for evidence from your own life, and it does so while the stakes are low: you can still change your mind, because nothing has been decided and nobody has quit anything.

It also makes a hard conversation concrete. Two people can disagree for months about whether they can manage on one income and never look at the same numbers. After three months of living it, the disagreement is usually about specific lines, and specific lines can be negotiated. If you are not yet sure you both want the same thing, start with when one of you is ready and the other is not, then come back.

Step 1: write the one-income budget

Start from what you really spend today, not from what you think you spend. If you can, pull three recent months of bank and card statements and sort every line into fixed costs (housing, utilities, loan payments, subscriptions) and flexible ones (food, transport, leisure, clothing, gifts).

1. 1

   Take the income that would remain

   Write the monthly take-home pay of the adult who would keep working: the amount that actually reaches the account. If you are a single person with a support plan, use your own pay plus any regular help you are certain of.

2. 2

   Copy your fixed costs as they are

   Housing, utilities, loans, phone. Do not trim them yet. If one of them would change because of the baby, such as a larger home or a car, mark it as a decision, not as a given.

3. 3

   Add the new lines as blanks

   Add rows for what a baby brings: diapers and feeding, clothes, childcare if any, and one-off gear. Leave every cell empty until you can fill it from a quote, a price you checked or a clearly labelled guess.

4. 4

   Remove what would go away, and only that

   List the work-related costs that stop when one adult is at home. Be honest: some costs disappear fully, some only partly.

5. 5

   Compare with today

   Subtract the new total from the one-income pay. The result is your monthly gap or your monthly margin. Write it down with today's date.

Costs also go away when one adult is at home (commuting, work clothes, lunches out) and new ones appear (diapers, home bills); list both. Do not worry if half the cells are blank at this stage; the rehearsal exists to fill them. For the full list of lines a baby can add, keep the hidden costs of a first baby open next to this page, and add a column that says where each number came from.

Step 2: the break-even table

The break-even question is simple: after the costs of working are subtracted, how much does the second paycheck really add? For some households the answer is a lot, for some almost nothing, and for many it is a surprise in one direction or the other. Fill in one copy of the table for each adult who is considering stepping back, and keep the headings the same for both.

To see how the table reads once it is filled, here is a worked example with fictional round numbers, in currency units. It is an illustration of the arithmetic, not a typical household.

Read the last two rows as a pair. A job can look small in cash and large once its perks are counted, or the other way round. Neither result is a recommendation; it is a number you did not have before, and two people can use it to ask better questions.

Step 3: the three-month dry run

Now live it. For three months, spend as if the second income were already gone, and treat the difference between your real income and the one-income budget as a transfer to savings, not as spare money. Three months is a suggestion: long enough to include a bill that does not come monthly, short enough that you can sustain it.

1. Before month 1

   Agree the rules

   Decide the monthly one-income budget, the start date and the account the difference goes into. Choose one person to move the money on the same day each month, and write down what would make you stop early.

2. Month 1

   Track everything, change little

   Record every expense, sorted into the lines of your budget. Do not try to be perfect. Note the surprises: the line that was larger than you thought, the one you forgot, the one you would never cut.

3. Month 2

   Adjust and test the blanks

   Try the new lines for real: ask for prices for childcare and for the items you would buy, and check what second-hand options exist. Replace guesses with quotes and move the amounts into the table.

4. Month 3

   Add the irregular costs

   Quarterly or yearly bills, repairs, gifts, a trip. They hide in a single month and change the picture. Keep moving the difference into savings, and write one sentence a week on how the household felt.

5. After month 3

   Read it together

   Sit down with the numbers, the savings balance and your notes, and use the questions below. Decide what happens next, and set a date to decide again.

How much to keep as a buffer is a separate question. A consumer-finance guide says in its guide to building an emergency fund that the right size depends on your situation, that you can start from the unexpected expenses you have had before, and that even a small amount gives some security. It also stresses saving consistently, for example by moving money automatically on the day it arrives. For a worksheet that sizes the buffer on your post-baby budget, see the baby savings plan and emergency fund.

Step 4: read the result together

The numbers are half the result. The other half is what you noticed, and it is easy to lose, so write the answers in the table below the same week you finish. Fill the last column with decisions (renegotiate a bill, move a purchase, ask for a quote), not with predictions.

If the test shows it does not fit as planned, that is a result, not a failure. The next moves are usually in the middle: a later start, a different split of hours, a smaller fixed cost, a longer saving period. The pre-baby shopping budget shows how to cap one line that tends to grow, so it does not eat the margin you just measured.

Count what is tied to the job

Childcare prices: look up your own area

Childcare is the line that varies most, and the one no average can answer for you. Ask nearby providers what they charge and how they charge: by the day, the hour or a fixed month. Two or three quotes are enough for a first row, each with the date you received it. If one parent is home only part of the week, count childcare for the uncovered hours, not the whole week.

Making it fair when one person earns nothing for a while

A single paycheck can make money feel like it belongs to one person. A few arrangements couples often find helpful, offered as suggestions and not as a formula:

• Treat the income as the household's. Say it out loud, and agree what that means for decisions about spending.
• Give each adult a personal allowance, the same amount for both, to spend without explaining.
• Count unpaid work. Looking after a baby and a home is work; list the tasks and look at them next to the paid hours, perhaps with a household task inventory.
• Keep the adult at home in the loop. They should know every account, bill and deadline, and be able to act on them.
• Plan a review date. Agree when you will look again at who works and how much, rather than treating the first answer as permanent.

The Greater Good Science Center's piece on how an unfair division of labor hurts a relationship makes a point worth keeping in mind here: what couples need is a split both of them experience as fair, not necessarily an exact 50/50, and the invisible work of remembering and planning counts alongside the visible tasks. Talking about it openly, early, is the common advice.

These ideas fit any household shape: two parents of any gender, a single parent with help, a partner who is not the one at home. Who steps back is a decision for the people involved, and the tables here favour no answer.

A conversation to have before month one

Pick a calm time and take turns with these prompts, five minutes each, without solving anything yet. If money talks are new for you, talking about money before the baby gives a longer agenda.

1. 1What do I hope the year looks like if the test goes well?
2. 2What worries me about living on one income, in one sentence?
3. 3What do I need from you during these three months?
4. 4What would make me want to stop the test early?
5. 5When do we sit down together to read the result?

Questions people ask