Twelve weeks before a due date is the sweet spot for money planning, not the frantic fortnight after the scan photos go up on the fridge. That’s when you still have the mental space to look at numbers calmly, before the nursery furniture and the sleep deprivation arrive together. A first-year budget built now gives you time to fix any gaps while you’re still earning two full incomes.

Pin Down Your Real Take-Home Figure First

Before you can plan a single nappy purchase, you need to know exactly what lands in your account each month once maternity or paternity pay kicks in. This is where a lot of budgets fall apart, because people plan around their current salary rather than the reduced figure they’ll actually be living on.

Statutory maternity pay drops sharply after the first six weeks, and shared parental leave splits the picture again. Map out, month by month, what each of you will genuinely receive from the point leave starts to the point you return to work. Write down the exact dates. A household that goes from two full salaries to one and a half needs to know when that dip begins, not just that it’s coming.

Separate the One-Off Buys From the Monthly Drains

A cot, a car seat and a pram are big numbers, but they hit once. The costs that quietly reshape your finances are the recurring ones: nappies, formula if you use it, wipes, the occasional clothing size jump, and the heating you’ll run more of during long days at home with a newborn.

Put these in two clearly labelled columns. The one-off list can be spread out, bought second-hand, or borrowed from friends whose children have outgrown things. The monthly list is the one that compounds, so it deserves the harder look. Some of the recurring pressure can be eased before the baby even arrives — for instance, the practical energy-saving projects rounded up on the babybudgeting website can trim the household running costs that become far more noticeable once someone is home all day. Trimming a fixed bill now frees up room for the variable ones later.

Run Your Numbers Through a Cost Calculator

Guessing at a total rarely works, because the small recurring items are easy to underestimate. A cost calculator forces you to enter each category and see the annual figure it produces, which is often larger than expected once nappies and feeding are multiplied across fifty-two weeks.

Feed in your real take-home figure from the first step, your fixed household bills, and the monthly baby costs you listed. The point isn’t to arrive at a single perfect number — it’s to see whether your projected income covers your projected outgoings across the leanest months. If it doesn’t, you’ve found that out with weeks to spare rather than in an overdraft.

Build a Buffer for the Surprises You Can’t Predict Yet

Even a careful plan meets the unplannable. A baby who won’t take one brand of formula, an extended hospital stay, a boiler that fails in the coldest week, or a return-to-work date that shifts because childcare falls through. These aren’t rare events; something in this category tends to happen to most new parents.

Aim to set aside a modest cushion before the birth — even a few hundred pounds tucked into a separate account changes how a bad week feels. If you’re in an area with higher childcare costs, and much of the South East and cities like Bristol and Manchester certainly qualify, weight the buffer a little heavier. Treat it as untouchable until an actual surprise arrives.

Schedule a Monthly Review You’ll Actually Stick To

A budget written once and never revisited drifts out of date within weeks. Pick a fixed day each month — payday is a natural anchor — and spend twenty minutes comparing what you planned against what actually happened. Adjust the next month accordingly.

Keep the review short enough that a tired parent will still do it. The goal is a running feel for whether you’re on track, not a spreadsheet marathon. Start the habit now, while it’s easy, and it’ll already be second nature by the time the baby arrives.

Do this groundwork in the months before the bump takes over, and the first year becomes something you steer rather than something that simply happens to your bank balance.