The invisible ledger nobody puts on the spreadsheet
There is a second set of costs that never makes it into the calculation. Skills go quiet when they are not used. Professional networks thin out. Confidence, in my experience, is the thing that erodes fastest and takes the longest to rebuild — many people who step back describe being perfectly capable of running a household of five and still feeling unqualified to answer a job advert two years later.
On the other side of the ledger sit things that are just as real: a child who is not being woken in the dark, a household that isn't running permanently at capacity, one adult who is not perpetually apologising to a manager for a temperature. Name both columns out loud. The couples who cope best with this arrangement are the ones who acknowledged the trade-offs at the start instead of discovering them in year three.
Try it before you commit to it
Wherever possible, test the arrangement before you make it permanent. A block of unpaid leave, a temporary four-day week, or a term of compressed hours will tell you more than months of theorising. Notice practical things: does the day feel long or full? Does the working parent come home to a partner or to a handover? Is anyone's world shrinking to the size of one postcode?
Build in a review date from the beginning — six months, then a year. Put it in the calendar like a dental appointment, because otherwise a temporary arrangement quietly becomes a permanent identity by default. A review is not a threat to the decision; it is what keeps the decision honest.
