Fair share of bills

[Chasingcars]

Hi
I currently rent one of my spare rooms to a colleague at work.
He pays �240 per month for 4 nights a week (he doesnt live in the area and travels back up North at weekends)
I bought one of the 'off the shelf'' legal tenancy agreements and under this i have the right to charge 'reasonable' costs towards bills - eg electricity, gas and water etc
However what is the correct way of working this out based on the fact he only lives in the house 4 nights a week? However he does have really really long showers and i am on a water meter!!
Any help would be gratefuly received - im sure its quite simple to work out but want to do it the 'correct' way!
Also he has been renting since Feb and its only now that i remember i can charge for these extra items - am i allowed to claim back payment for them or would that be unreasonable even though we both discussed it initially when he started lodging ?
Thanks

[Buenchico]

I'll tackle this firstly from a mathematical viewpoint, and then from a legal one.

You're present for 7 nights per week, while your colleague is present for 4 nights. That means that there are 11 'person-nights' involved, four of which relate to your colleague. Therefore he should pay 4 elevenths of the bills. That's about 36.4%. However, that might be a bit high because you're also using the utility services during the day (as well as the evenings and mornings) at weekends, when he is not. So it would seem more reasonable to charge him around 30% (or, at the most, one third) of the bills.

Your question about whether you can back-date the bills could keep teams of lawyers busy for months ;-) Your lawyers would argue that your initial discussions represented a legal contract, thus giving you the right to bill your colleague for utility charges since February. His lawyers would argue that you'd told him how much he owed you each month and that each payment was a separate contract. Since he'd paid the full amount demanded at the time, they would say that he had completed his contractual obligation and you have no right to demand further payments.

I suggest that you should remind your colleague of the original agreement, and levy charges of around 30% of the utility bills from now, but write-off any charges relating to previous months.

Chris

[bundleone]

I would have thought the rent he paid as a lodger would cover his keep

[taperface]

Oh blimey, Chase! Isn't �240 a month enough to cover the poor man's electricity, gas and water? I could understand your concern if he was always using your phone for nothing as well, but for a roof over his head for a mere four nights a week, I think you're pushing it!

[Chasingcars]

Thanks for your comments, this is helpful
What I may not have made clear initially is that the signed agreement we both signed states that he has to make these contributions towards gas/ electric, water etc
Appreciate this may seem trivial taking into account that he does pay �240, however he is hard work. For example I always have to chase him to do his washing up, he expects that if he leaves it lying around long enough i wil do it!
He never cleans his room unless I chase
He always leaves his bathroom in a mess when he leaves for weekends. Dont get me wrong, im no Kim n Aggie but basic things like washing out sinks and picking up dirty towers shouldnt be too difficult
I therefore find myself spending my weekends picking up after him, so perhaps a reminder that he should be paying towards bills etc will remind him that i wnt be taken advantage of?
Also to add, im on water meter, he showers for ages, always leaves taps running when he washes up and does his teeth, and has his laptop plugged in all hours of the day and leaves lights on in the whole house when im not there!
Maybe my suggestion to pay towards these extras may remind him to be a bit more thoughtful?