Bird moving into my gaff - what’s fair to charge her?

500-sex=?

The world is moving towards usage billing.

Put a tracker on her and work out a formula where she's charged for each step she takes in your apartment, as well as a rate per minute that she spends inside it, so she doesn't get away with just standing still. You need to be careful that she doesn't start hopping to scam you out of ever second step. She also needs to wear a spirometer, so you can measure how much of your air she is breathing, and charge her accordingly. Don't forget to add a carbon tax for all CO2 exhalation. Weigh her before and after using the toilet, so you know how much mass she's expelling, and charge per gram.

For utilities, she should keep detailed records of every time she flicks a light switch or turns on or off an appliance. If you are in the room when a light goes on, she should be charged a half rate per second, same if she's watching television with you or she boils the kettle to make you both a cup of tea (assuming you both use the same amount of water and milk). It gets awkward when, for instance, you're watching television together, and she glances momentarily at her phone, or out the window. Technically during this time she is not using the visual aspect of the television (although she is still consuming the sound), so some adjustments will have to be made unless you can find a way to measure the source of all photons that enter he eyes. Although obviously there should be a charge for using the view out your window. Whether that's the same as the charge for looking at your television is up to you, but it would make things simpler if it was.

For food, again detailed records should be kept, and charges made accordingly. A lot of people forget that storing food takes up space that should be paid for too. So when setting the rates you charge her for each food item, don't just base it off the cost of buying the food itself, but the cupboard or fridge space, the cost of bringing it to your home, the cost of unpacking it, wear and tear on your shopping bags, etc.

Finally, your physical company and social interaction should be compensated for too. Set a per word rate on conversations, both for speech and listening. Be careful, tough, that she doesn't use a lot of long words to get a protracted conversation at a discounted rate. Any physical interaction should be charged based on a detailed price list, with a diagram of your body divided into sections at various per-second rates.

Show her your stripes now: ask for 2k per month, with an annual adjustment based on the inflation rate.

She'll be having a lucky escape....

Good point. There should be a charge for hiding sausages or any other food stuff not limited to processed pork products on your property, OP. Also a charge for her having any guest, visitor or interlocutor in your apartment, whether they’re engaged in sausage/miscellaneous item hiding or not.

The OP could be an older gentleman with a younger partner (the "bird")? It takes to age 55 for a majority to own their home outright. But they could be an exception who had independent wealth entering the property market. I would expect a different dynamic depending on the age difference and the economic resources of both parties.

The point at which two-thirds of householders owned their own homes (with or without a loan) occurred at age 41 in 2016, while in 1991 the equivalent age for that particular milestone occurred at 28 years of age. The age at which the majority of householders owned their dwelling outright stood at 55 years in the last census, which has changed little since 1991 (56 years). (Census 2016).

Jayssssussss... All the smart-ass answers make me laugh...

It's an 18 month relationship - which, as we all know can go either way!

He needs to protect himself IF the worst happens - and she can't expect to live in HIS gaff for free!

So deffo 50/50 on bills/groceries/etc... but the "rent" (and legal mumbo jumbo) is a tricky one alright!

It will only be a matter of time before she starts bringing friends over.

Installing a coin operated bathroom lock on the loo might honestly be the only fair way forward.

Unless she’s a total birdbrain she would have sussed @Ham Grenade after a year and a half.

She should pay for absolutely everything, considering the privilege to be living with you.

Just guessing, but this is gonna be the shortest togetherlivingrelationship ever.

Probably not, after they'll discuss the cost of "rent". But credit to OP he asked for advice.

Methinks you'll be on tinder fairly soon and she will be snuggling up to someone nicer

That's for England and Wales. Anyone who wants a legally binding cohabitation agreement should set it up with a solicitor.

Read this:

https://www.citizensinformation.ie/en/birth_family_relationships/problems_in_marriages_and_other_relationships/redress_scheme_for_cohabiting_couples.html