Your proposal seems fair to me.

My wife and I lived together for a bit back when we were dating. We did some math:

Combined rent + $savings = my old rent + her old rent

Then we split the combined rent roughly 1/3 - 2/3 (my salary was higher than hers at the time) so that we were both paying less than we had been before.

We split utilities 50/50 which was kind of a mistake IMO – I regret the accounting chore that it created. One of us would pay the rent by hand (USA, so paper check to the landlord), but utilities were on auto-pay from my account. We’d have to tally up utilities and add it or subtract it to the rent in order to reimburse the other person when they paid the rent.

Instead of that nonsense, I’d suggest estimating your utilities and split that figure 50/50 - then maybe look at it again once a year in case costs change.

if she helps pay the mortgage or renovations or anything that increases the value of the house she gets to own part of the house otherwise its completely unfair, split utilities according to income and thats it.

Probably best to let her dictate the price though since there is such an imbalance of power at play

My advice is not financial but rather about relationships:

• Money and finances are one of the top things couples fight about.
• Psychologists have observed that couples have the same disagreements (or fights) over the long term course of a relationship, and these can be used as touchpoints to assess the couple’s emotional maturity and overall relationship health.
• So, whatever financial arrangement you agree upon, commit to it in a way that actively reinforces the importance of the relationship, fosters open communication, and strengthens your bond with one another.

Not a financial advisor so take my answer with a massive chunk of salt.

My suggestion would be to get a joint account. If you are comfortable paying all the bills you can also have it overdraft to your account in case of emergencies. The move money into it monthly for bills. I would round up on your bills so you could build a little nest egg at the same time. You move everything that you have been paying into it. And ask her to move what she can into it. If she feels comfortable paying 50%, then do that. If things go sideways, split any extra money by the percentage she is paying. Then if things do go sideways then you can take your piece and have a nice vacation. If they don’t, you have nice rainy day fund.

Holy shit. I’m worried about everyone suggesting she pay no rent.

Stumbled into c/relationshipmath over here

This varies by person, and he best person to talk about this is your girlfriend.

With that said, I’d do half what she paid in rent for mortgage (of half the mortgage payment, whichever is smaller), and all other expenses split down the middle. She would pay rent if she lived elsewhere, the way I see it, her contributing to the mortgage is a deeply discounted rent.

This might not work for you, you need to talk. Me and my now husband when we first started setup a joint account, and each sent half of an agreed amount there every month, or as needed. We didn’t make similar incomes, it fluctuated back and forth through the years for both of us. Some people would think it was unfair for us to pay the same. It worked for us, and both of us were happy with the arranjement, it might not be the best option for you.

As others have said, there is no right answer but here are my thoughts based on my experience.

Mortgage

The apartment is under your name so I would expect you to pay the mortgage.

One thing you could do is that your girlfriend puts a share of the mortgage cost into a savings account under her name. It could be the equivalent of what she’s paying now for her rent of the equivalent of your mortgage minus 30%.

This way if you stay together and decide to buy a new home you can both contribute to it with a nice down payment and if you split up you both get your marbles back.

It also levels your salaries and you are contributing equally to the housing cost so there is no resentment being built on your side.

Utilities and groceries

What I did with my girlfriend (now wife) is that we were doing a pro rata monthly contribution to a bank account that was used for everyday life. In your case you are earning 30% more then you can contribute 30% more to this account. Then everything like electricity, groceries, restaurants together … Was deducted from this account.

It’s quite easy to get a free bank account with two cards so we used that (we used N26 at the time but there are plenty of options, the bank account was technically a single person account with two cards but it did not really matter since we were not keeping a lot of money in it). We started by keeping track of all our expenses on an app like Tricount and regularly balancing our contribution, it’s easy to set up but it requires to keep track of all our expenses and was quite annoying to do on the long term.

It’s up to both of you. Don’t rely on social norms because it almost always leads to disagreement or when something changes someone feels it’s unfair.

Sit down together and decide what’s fair for your current situation and revisit it every time you adjust the budget. That can be as often as every week or month. Don’t lock yourselves into 1 agreement for ever. Expect it to be fluid and change as your financial situation changes.

As long as you’re both happy with it, it’s fair.

My partner and I split all costs based on what we are able to commit to (roughly proportional to income)

You should split groceries/electricity and all that 50/50. The house is yours so she should not pay for it unless you actually both agree she should pay a monthly rent to live in your house. That to me would be correct. I am in a different situation as you as I bought the house with my wife and even tho I spent more because I had more money available I did not ask her extra money. Also keep in mind that wife is different than girlfriend. So since wife>girlfriend I honestly thing you should get to an agreement with your girlfirend and she should actually pay something for the rent and it should not be all on you.

If you’re keeping the apartment only in your name I think it’s fair only you pay the mortgage, she can pay half of everything else that she does benefit from/has to pay for in her current living situation anyways

Either way this is something you need to talk about with her and see what both of you are comfortable with. Se might not agree to whatever some stranger on lemmy thinks

Like others have said, one option is to have a chat with her.

Another option could be coming up with a percentage that fits your 30% increase in earnings:

Assuming you start with a 50/50 split, we can add a 30% increase to your share:

0.5 * (1 + 0.3) = 0.65

This 30% increase leads to a 65/35 ratio, where you would be paying 65%, and she 35%.

I personally would feel weird collecting rent money from my girlfriend that provides me equity. Did you ask her what she thinks?