Sharing broadband with neighbours, lodgers or guests

"You and your household". A neighbour, or the family in the flat downstairs, is a separate household, so sharing with them sits outside this wording before you even reach a specific ban.

"Resell" or "make a charge". Taking money for access looks like reselling, even if you only want to cover costs.

"Permanent or regular basis". YouFibre's wording separates a friend who joins your Wi-Fi now and then from an outsider who relies on your connection every day.

The terms we read describe the consequences in general language rather than fixed penalties. Vodafone says failing to use the service for private, personal and legitimate consumer purposes may lead to loss of, or restriction to, the service. WightFibre says that if it considers a breach serious it may reduce, suspend or end your services without notice.

BT's terms are the most detailed. Clause 11b says that if you break the agreement BT will normally let you put things right within a reasonable time, but it may limit, suspend or end a service straight away in listed cases, which include using the service for any trade, business or profession and usage that is "significantly different" from what it would expect from the average customer. If that happens during your minimum term, clause 11e says you'd have to pay a fee for leaving early, and for most of the listed reasons BT may also charge to restart the service.

Some terms say the provider may review how you use the service (Zzoomm, clause 9.2, mentions data volume and type of traffic) or act if your usage is very different from an average customer's (BT), but we found nothing published on how providers spot sharing specifically, so we can't say how likely it is to be noticed.

What the law says about recharging bills. GOV.UK's "Rent a room" guidance says a resident landlord who pays the bills can include a charge for them in the rent, but for gas and electricity they can only charge what they paid plus VAT, under Ofgem's resale rules. That page doesn't mention broadband, and we found no equivalent rule for internet access.

What your provider's terms say. This is the bigger issue: WightFibre bans making any charge for using the services, Virgin Media, Vodafone, YouFibre, Rebel and toob ban reselling, and Hyperoptic's Acceptable Usage Policy bans selling or re-selling any part of its services. An all-inclusive rent where broadband is simply one of the things the room comes with may be read differently from a separate "Wi-Fi fee", but the terms we read don't spell that out. If you want to include broadband in what your lodger pays, ask your provider in writing how it treats that.

If you let several rooms to people who aren't one household, you may be running a house in multiple occupation (HMO). GOV.UK defines an HMO as a property rented out by at least 3 people who aren't from 1 household but share facilities like the bathroom and kitchen. In England or Wales a large HMO (rented to 5 or more people forming more than one household who share toilet, bathroom or kitchen facilities, with at least one tenant paying rent) needs a licence, and councils can require licences for smaller HMOs too. Scotland and Northern Ireland have their own rules. Broadband in that setting is covered in our guide for landlords providing broadband to tenants.

Providers only pursue the person named on the account, so if you're the account holder and a housemate or lodger stops paying their share, recovering it is down to you. Our guide to changing the broadband account holder explains why the account holder matters and what to do when a housemate moves out.

In practice that means the account holder carries all of the financial risk and all of the responsibility for how the connection is used. If your lodger would rather have a connection in their own name, see two broadband lines at one address for how a second line in the same home works. Students sharing a house will find more on choosing an account holder in our guide to broadband for students.

You answer for their use. Gigaclear, Zzoomm and Connect Fibre all treat someone with access to your home as within your control, and Gigaclear gives illegal downloading of copyright material as an example of unlawful use you could be held liable for.

Any complaint lands on you. A rights holder who traces activity to an IP address (the number your connection uses online) has to get the name and address behind it from the provider, which means the account holder's details: that's what the claimants sought from O2 in the 2012 High Court case Golden Eye v Telefonica, where the judge also recognised the subscriber may not be the person responsible. Our guide to copyright infringement letters covers what to do if one arrives.

The bill is yours alone. If the arrangement with your neighbour falls apart, there's no route to make the provider collect their share: it will only pursue you as the named account holder.

Your devices may be exposed. Anyone on your main Wi-Fi is on the same home network as your laptops, phones and smart devices, which is exactly what a guest network (below) is designed to avoid.

If your neighbour is sharing because they think broadband is out of reach, there are usually better routes:

• Their own connection. They can compare broadband deals at their postcode, including cheaper broadband deals and broadband-only deals without a landline package.
• A social tariff. Citizens Advice explains that people on certain benefits may be able to get a cheaper deal called a social tariff, depending on which benefits they get. Our social tariffs guide sets out the eligibility rules and the application steps.
• Help getting online. If cost or confidence is the barrier, our guide to free and low-cost internet access covers other options.

Refuge's guide sets out the general steps: log in to your router as the administrator, find the guest network settings, turn guest access on, then give the guest network its own name and a strong, unique password that's different from your main Wi-Fi password. For the admin password and other router settings, see how to secure your home router and Wi-Fi.

A few points from Apple's recommended router settings apply directly to guest networks:

• use WPA3 Personal, or WPA2/WPA3 Transitional if older devices need it, and otherwise WPA2 Personal (AES); avoid WEP and TKIP;
• don't leave any network open, including the guest one: Apple strongly discourages turning security off;
• a hidden network name isn't a security measure, and Apple says not to rely on MAC address filtering (letting only listed devices join);
• keep the router's firmware up to date.

To avoid reading the password out, Android phones can share Wi-Fi details as a QR code that a guest's device scans. On many Android phones (menu names vary by manufacturer), open Settings, go to Network and Internet, then Internet, choose the network and tap Share. If you can't remember the password in the first place, our guide to finding a forgotten Wi-Fi password will help. Change the guest password when a lodger moves out.