Revealed: The Annual Cost of an Adult Child Living at Home (and Tips to Encourage Their Independence)

No rent, food magically appearing in the fridge, and the washing done on demand — it’s no surprise that some adult children choose to stay in the family home.

However, an increasing number of young adults feel compelled to live with their parents due to the high costs of moving out. Rising rental, food, and energy expenses — not to mention housing prices — have made saving for a deposit increasingly difficult.

A staggering 3.6 million people aged 18 to 34 still live at home, accounting for 28 percent of that age group, according to official data. Men are more likely to share a roof with their parents, with a third of men under 34 living at home, compared to around a fifth of women.

This trend means millions of parents are bearing a greater financial burden for longer periods, absorbing the added costs. It can be challenging to start demanding rent after decades of having them under your roof, especially if they are staying in their childhood bedroom.

But how much extra does it really cost to have them at home? How much rent is fair, and what is the best way to help them become financially independent?

Money Mail crunches the numbers and consults professional financial planners for answers.

Calculations for Money Mail by investment group Bestinvest by Evelyn Partners have found that, on average, parents spend an additional £3,684 each year (£307 a month) on energy, food, and water bills when one adult child lives at home. This amounts to an extra £62,628 if the child stays from age 18 until 34. The cost rises to £6,252 a year for two adult children (£521 a month).

Alice Haine, personal finance analyst at Bestinvest, says: ‘While many parents might welcome the return of their adult children, they may rethink when they see their beloved offspring consuming their groceries, enjoying long, hot showers, and filling up the washing machine.’

Food is the largest expense. The average monthly food budget for two adults in the UK is £415, according to analysis by data group NimbleFins. This includes £320 for groceries and £95 for takeaways and dining out. For three adults, this jumps to £622 a month — £480 for groceries and £142 for eating out. That’s an extra £207 a month.

Energy costs also increase. The average annual energy bill is currently £1,690, or £141 a month, according to the Ofgem Energy Price Cap. This is based on a medium-sized home with two to three occupants. With one or two adult children returning home, the cost can jump to £2,365 a year, or £197 a month, an increase of £56 a month.

Water bills vary by region, but the number of occupants impacts the cost. The average monthly bill for a household of two is £34, according to Southern Water. Adding one more occupant raises it to £44, and for two more people, it’s £51.

In reality, the overall cost of having your offspring at home could be higher, says Ms Haine: ‘Parents might make additional purchases and buy gifts for their children, further straining their budget.’

Parents whose children have left home generally don’t expect them to return, so they may not have budgeted for the extra costs. Charging an adult child rent or a contribution toward bills can be a good idea, says Ms Haine. But how much?

A survey by Comparethemarket found that over half of parents charged their children rent for living at home beyond age 18, but often as a token gesture. On average, they charged £25.55 per week, or £110.71 per month, far lower than the average UK rent of £1,223 per month.

Charging market rent might not be wise, as it could hinder your child’s ability to save and move out. Ms Haine suggests: ‘A rent that covers the financial burden of an extra person in the house shouldn’t be so high that it delays their ability to save and live independently.’

You can calculate the added cost by monitoring increases in your bills and the weekly shop. Alternatively, charging £307 a month should cover the extras on energy, food, and water.

A property is considered affordable if you spend 30 percent or less of your income on rent. Charging your adult children 15 percent of their income would allow them to save, says Ms Haine.

As a general rule, don’t charge close to the average rent in your area, but ask them to cover basic costs at a minimum. If parents want to help their child save faster, charging 10 percent of their income could be preferable, provided it covers the parents’ costs.

Charging nothing at all may not be the best option. Adults who receive significant financial help from parents are more likely to make impulse purchases and lack emergency savings, according to a survey by Wealthify.

Michelle Holgate, a financial planner at RBC Brewin Dolphin, suggests that getting adult children to pay some bills can help build their credit score, improving their chances of securing a mortgage.

However, assess their financial situation before asking for large contributions. For example, consider if they are in debt and need to prioritize repayments.

Neil Rayner, head of advice at True Potential, suggests parents could save any rent payments towards a house deposit for their children. Putting £450 a month into a stocks and shares ISA with a 6 percent annual return could result in £31,553 in five years — enough for a deposit on an average house.

If your child is a higher earner, you might be tempted to charge more rent, but Ms Haine warns against this. ‘Treat your children equally and charge an affordable amount. Don’t penalize one for earning more by asking for higher rent. Charge them enough to cover the bills, but not so much that it hinders their savings prospects.’