Share your insights or perspective on the financial matter presented in the input.

Currently sole owner of a property. My girlfriend is looking to move in with me and is offering to pay 'rent'. Am I at risk here?
The rent payment is in principle taxable. However, you should be able to take advantage of the "rent a room" scheme, and the proposed rent falls well under the £7,500/year tax threshold for that. So no tax will be actually payable and you don't have to formally declare it as long as you stay below that threshold. You should also be fairly well legally protected in case you do split up in future and you want to remove her. As you would be living there too, she would just be a lodger, not a tenant (technically, an "excluded occupier"). If you did want her to leave you would only need to give reasonable notice and wouldn't need a formal court order if you needed to force her to go. As JBentley points out, there have been court cases where domestic partners contributing to household expenses while the other partner paid the mortgage have later been able to claim that this implied joint ownership. This was on the basis of a "constructive trust" being implicitly setup by the way they arranged their finances. In your case, if there's a clear intention, formalised in writing, for the money to be treated as rent rather than a contribution towards purchasing the property, I think it should make it very hard to claim the contrary later. I would also suggest you be clear about whether the rent includes a share of the utility bills, and that things like groceries would be handled separately and split 50:50 or whatever. As pointed out in a comment, there are template agreements for lodgers you could use a starting point (e.g. this one), but it's likely you'd need to customise it to your circumstances. Another point made in another answer is that there's potential upcoming legislation to give some rights to cohabiting partners. In the current draft, those would kick in after three years or having children. If the bill does come into effect, you'd also be able to sign an opt out, but only after getting legal advice, and it would still be possible (though presumably hard) to persuade a court to overturn an opt out. Overall that does create a small risk to you, but not one that comes directly from your girlfriend paying rent. It's likely that if you are both on an equal financial footing and had always kept your finances separate, that there wouldn't be any award made anyway. And you can't run your entire life on hypothetical risks.