As with sub-letting, taking in a lodger should not result in overcrowding and must meet our standards for houses in multiple occupation.
Taking in a lodger will also probably affect the amount of benefits you get if you're claiming. For example, if you're receiving housing benefit and you take in a lodger, the amount you get will almost certainly be reduced as it will be assumed that your lodger is paying rent. This will be the case even if your lodger is living rent-free. If you simply don't tell them, you may end up having to repay an overpayment or be prosecuted for fraud. This also applies to income support and Jobseeker's allowance (JSA); the amount of council tax you have to pay may increase.
Renting out a room may also affect your contents insurance. Most insurers will put up premiums, but it's still important to inform them if you want to be sure that your belongings are protected. If you don't tell them, the insurance may not be valid.
If the income from letting a room exceeds a certain amount, then you may also be liable to pay income tax.
You will be the lodger's landlord, and will have the responsibilities of a landlord.