Electricity and gas bills as a couple: three ways to split them

The oldest bill in cohabitation

Electricity and gas are the oldest category of shared expense in the book, and even so they remain, in many couples, the silent source of a disproportionate share of small domestic tensions. The reason isn't the money. An average monthly electricity bill for a couple in 2026, in an urban flat with reasonable consumption, ranges between 80 and 130 euros. The gas one, in cold months, can rise to 150 or 200. Added up over the year, we're talking about 2,000 to 3,500 euros a year in basic utilities. It isn't trivial, but it isn't what breaks the budget either. What breaks things is the feeling.

The feeling, in a couple, comes from two questions rarely asked explicitly: who's getting more out of this bill? and what does "fair" mean for this particular couple? The first has a more or less objective answer if you observe carefully. The second is intimately subjective, depending on each person's history, on the incomes, on the habits, on the beliefs about shared money. The curious thing is that most couples agree the splitting model in the first few months, without ever having had those two conversations, and then live for twenty years with the initial decision without ever revisiting it.

That's where the noise comes from. Not from the model itself, but from its rigidity in the face of a life that changes.

Why the models change without the couple deciding it

A fact almost nobody notices: couples who have lived together for years have almost always mixed models without formalising the change. They started fifty-fifty, at some point one began working from home and they tacitly adjusted one bill, then they changed again when one switched jobs and the incomes became unbalanced, and now they pay electricity fifty-fifty, gas sixty-forty and water depending on who's home. When someone from outside asks them how they split the utilities, they can't answer precisely.

It isn't wrong. It's poorly articulated. And "poorly articulated" is the raw material of the small arguments that surface on the least expected day, when one of the two has had a rough week and suddenly, looking at the last bill, thinks "hang on, why am I paying more for this if it was his idea to blast the air conditioning all August?". The problem isn't the August air conditioning. The problem is that the model wasn't written down.

Three coherent models (and choosing one explicitly)

1. Fifty-fifty

The simplest model and, surprisingly, the most reasonable when the couple's usage patterns are comparable. If both members spend similar amounts of time at home, have similar energy consumption and the incomes aren't radically different, splitting each bill fifty-fifty saves an enormous amount of mental energy. One month a bill is a bit higher because one of you showered more, another month it's because the other turned on the heating earlier; in the long run, it evens out.

The virtue of the model is its simplicity. The weakness is its rigidity: if at some point reality changes a lot (one starts working from home, one moves partly out, one switches jobs), fifty-fifty stops reflecting anything and starts generating friction.

A plausible example: a combined electricity-plus-gas bill of 178 euros. Each pays 89. If the usage pattern is even, this is the cleanest thing you can do.

2. Proportional to usage (especially with asymmetric working from home)

This model comes in when one works from home several days a week and the other is out of the house all day. The continuous presence of one person drives up the electricity consumption (lighting, computer, an extra monitor, the water heater for coffee, local heating in winter) measurably. Sticking to fifty-fifty in the face of a clearly asymmetric pattern is comfortable for one and expensive for the other.

A sensible formula: the contract's fixed charge (the contracted power, the standing gas charge) is split fifty-fifty (the couple pays that simply by having a home), and the variable component is split proportionally to presence or usage. On an electricity bill of 110 euros with 35 euros of fixed charge and 75 euros of variable: 17.50 fifty-fifty on the fixed part, and 75 euros divided by presence. If one accumulates 22 days at home a month and the other 8, the variable proportion is roughly 73-27, so 54.75 against 20.25. Added to the fixed part: 72.25 euros for one, 37.75 for the other. The bill feels fair because it reflects reality.

It's more laborious. It works if the couple has the discipline to note days of presence or to accept an estimate agreed at the start of the term. If that discipline doesn't exist, the model crumbles and reverts to the first out of exhaustion.

3. Proportional to income

The most underused option and the one that makes the most sense when there are significant income differences and the couple understands shared expenses as a joint effort, not as a symmetric transaction. If one earns 2,800 euros net and the other 1,700, the natural split is roughly 62-38. On a bill of 178 euros, that's 110.36 against 67.64. Both feel a proportional pinch, not an absolute one.

The model fits couples that are stable, with a medium-term outlook and comfort talking about money transparently. It doesn't fit new couples, nor when one of the two isn't comfortable sharing net figures. It's a more mature model, not a more "correct" one. Both options are legitimate; what matters is that the couple chooses consciously.

The most common mistake: applying two models at once without realising

Most of the small tensions over utilities don't come from choosing the wrong model, they come from having one implicit and one explicit model that coexist badly. A couple that says it splits fifty-fifty, but one pays rent proportional to income and then expects the electricity to feel proportional too. A couple that splits electricity by usage, but gas fifty-fifty because "it doesn't matter". The human brain doesn't handle these inconsistencies well: when the moment to pay arrives, the sense of unfairness shows up without the person being able to articulate exactly why.

The cure is simple in the abstract and demanding in practice: a fifteen-minute conversation where the couple explicitly decides which model applies to each block of expenses (rent, electricity and gas, supermarket, leisure, IBI, holidays), writes it down somewhere, and commits to reviewing it once a year. The conversation is awkward only the first time. After that, what's awkward is not having had it.

How to close out the bills without turning them into a topic

The mechanical part of the monthly close-out should be invisible. Any decent system for couples should let you log the bill once, assign the agreed splitting model for that category and leave the balance between the two of you visible and up to date. ControlarGastos does exactly that, and it splits the cents by largest remainder, not by truncation, which matters when you're talking about a 62-38 split on a bill of 178.33 and you don't want it always to be the same person paying the rounding cent.

The human part is what makes the work worthwhile. A couple that doesn't fight every month over the gas bill has thirty minutes freed up each month to talk about anything else. Ten years into the relationship, that's sixty hours not spent arguing over whether it was reasonable to turn the heating up a degree when it was raining.

Conclusion: the fair split isn't the mathematical one, it's the explicit one

The right question isn't "which model is mathematically fair?". It's "which model fits how we are and do we apply it consistently?". A couple that splits everything fifty-fifty consciously, knowing it, choosing it, is far more stable than a couple that believes it splits proportionally to income but in reality mixes three models without noticing.

Electricity and gas don't break relationships. What breaks them is the sum of small asymmetries that nobody articulated. Articulating them, once a year, in a calm conversation, is one of the most profitable financial gestures a couple can make.