Adult children moving back home: what it really costs parents

The rising cost of living is making it harder than ever for young people to fly the nest and stay flown. We spoke to two parents from the Boring Money community about the financial realities of having adult children back at home.

Why are more adult children living with their parents?

The numbers speak for themselves. The average room in a shared London flat now costs £985 a month[1], up 37% in just five years. The average first-time buyer in 2024 paid £311,034[2] for their property and needed a deposit of around £61,090[2] to get there. Meanwhile, the average age at which people buy their first home in England has risen from 32 before the pandemic to 34 today[3], and 35 in London. In the 1990s, the average age was just 29.

With many renters therefore now spending 40% or even 50% of their income on rent alone, it's perhaps no surprise then that 28% of all 20–34 year olds[4] (3.6 million people) were living with their parents in 2024, up from 25.6% a decade earlier. For men in that age group, it's closer to one in three.

We asked two parents living this reality how they're navigating it.

Sarah, retired teacher, Hertfordshire — two sons, 28 and 29

Both of Sarah's sons graduated in 2019 and moved straight back home. There have been gaps where one rented in Watford for two years with a friend, and the other relocated to Norfolk for a year to work remotely and pursue a passion for birdwatching, but the economics of living near London kept pulling them back. Now, just her younger son, Gregor, lives at home with his girlfriend. "I really understand - living just outside London, it's just not possible for them," she says.

How much rent should you charge an adult child living at home?

Yes to charging, but deliberately not too much. Sarah started at around £200–300 a month when they first returned, "just something to get them used to paying." Currently Gregor and his girlfriend contribute £500 a month between them. They buy and cook their own food; the contribution is framed as covering heating and hot water. Gregor works from home, so this felt particularly relevant.

"I feel it's important that he doesn't pay me any more than he needs to. He should have that money to put towards a deposit for his own place."

Sarah also mentions she lost her single-person council tax discount when her sons came back, so part of what they pay covers that gap.

Can adult children use a Lifetime ISA to buy near London?

Sarah's older son Cameron, and his girlfriend both had Lifetime ISAs, but the flat they bought in Waltham Abbey exceeded the £450,000 LISA property price cap. The property sat just outside the London boundary, so they'd expected to be eligible. "They managed to do it, but it was rushed," she says. It's a reminder that while the LISA is a useful product for first-time buyers saving in lower-cost areas, the cap can catch people out across the commuter belt, where many young people are trying to buy.

How does having an adult child at home affect your own finances?

Sarah is trying to sell her house and move in with her partner. There was initially no room for him to move in when both children were living at home. In an ideal world, she would be looking for something smaller, but is currently looking at similar sized homes as she needs space for her son and his girlfriend. Her partner also has an adult child at home, which means moving in together isn't straightforward. There's also no certain point at which Gregor and his girlfriend will move out – they are planning to travel from July, but when they return in March, they'll need to live with Sarah for another six months or so while applying for a mortgage. "It's the least I can do," she says.

Robert, retired, Cheshire — two sons, 25 and 28

Robert has two sons at home: Joe, 28, and Harry, 25. Joe is back temporarily following a relationship breakdown. He's paying 50% of the mortgage on a property he no longer lives in while they untangle their finances. He'd previously bought a flat with his then-partner, a process Robert remembers with disbelief. "He was going to see houses for £250,000, putting in offers of £265,000 and finding out he'd been outbid. It was just ridiculous."

How much rent should you charge an adult child living at home?

That depends on the son. Joe has never been charged rent; not when he first came back to save for his house, and not now. "I knew he was saving," Robert says simply. "He still had quite an active social life, but he was saving hard."

Harry is a different matter. "His bank account is well and truly exhausted by the day before payday." When Harry turned 25, Robert started charging him £100 a week, but with a twist: Harry doesn't know that Robert has been secretly saving every penny for him. It now sits in a money market fund

via AJ Bell to be handed back as a lump sum when Harry eventually moves out.

Harry begrudges the rent, Robert admits cheerfully — but points out that a flat in Manchester would run to around £1,500 a month, making £100 a week look very reasonable indeed.

How does having adult children at home affect your own finances?

"My surplus is smaller," Robert says. "But that's all." He and his wife had been thinking about downsizing from their five-bedroom house, but that's on hold for now, and Robert is fine with it. "If we didn't help him this way, we'd have to help him with the deposit or something. You've got to do it, haven't you?"

What should parents do if an adult child moves back home?

Both Robert and Sarah arrived at sensible approaches organically. A few themes emerged from our conversations that are worth considering if you're in a similar position.

Decide what the rent is actually for. Are you charging to cover your costs, to instil financial discipline, or to quietly save on their behalf? The answer shapes the amount and how you handle it. Robert's approach of charging Harry and saving it back without telling him works because he wouldn't save independently. Sarah keeps Gregor's rent low because she trusts him to put the difference towards a deposit himself.

Factor in the hidden costs. Lost council tax discounts, higher utility bills, and the delayed ability to downsize are all real financial impacts, even if they're not necessarily things you'd think of at first, and can be hard to quantify precisely.

Check whether a Lifetime ISA will really work for them. The government adds a 25% bonus on up to £4,000 saved per year. But you can only use it to buy properties worth up to £450,000 — even if contributing with two LISAs, which can catch buyers out in commuter-belt areas outside London. Check before they commit years of saving to a product they may not be able to use.

Have the deposit conversation early. Both Robert and Sarah contributed lump sums towards deposits without a formal plan. If you're able to help, clarity on how much, when, and on what terms prevents awkwardness — and even conflict — later.

Don't neglect your own financial position. It's easy to subordinate your plans to your children's needs. But if you're delaying downsizing, dipping into savings, or putting retirement plans on hold, run the numbers. It's great that you're helping — but it shouldn't mean compromising yourself.

___

[1] SpareRoom Quarterly Rental Index, Q4 2025 / Annual Rental Market Summary 2025.

[2] Average first-time buyer house price and deposit, UK Finance / Finder.com, 2024 data.

[3] English Housing Survey 2024/25, Chapter 3: Housing History. Gov.uk, December 2025.

[4] ONS Families and Households in the UK: 2024. Office for National Statistics, July 2025.