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.

There are a million possibilities and no single right answer. Strangers on the internet are not going to be able to tell you. Strangers on the internet certainly don’t know the dynamic between the two of you.

Write down the possibilities (you’ve mentioned some in your post). Think of what seems fair to you. Show her the possibilities and talk about it and agree something.

My wife came from a family that considered it the man’s duty to pay for everything and that women have to protect themselves from exploitation by guarding their own money. Conversations about sharing expenses were very unwelcome and showing love meant spending a lot on luxury gifts. She used to earn a third of what i did and had more disposable income than me since bills left me with little disposable. You could end up with 2 people at different levels of affluence in the same house if you are very defensive and financially isolationist. It’s taken a long time to change that to a collaboration to work through life together with shared resources.

The most “scientific” way in a full commitment would be to put an equal % of both salaries into a “bills” account, then put how much you both want to save into a savings account and then divide the leftover disposable equally between yourselves.

Or if you’re too early to be fully committed then you can start with continuing to pay for everything or ask her for a flat amount contribution.

Just know that money is one of the biggest sources of friction on a relationship and most people at not on the same page. It takes work and talking to get to the same page (that means talking to her… Not us).

When my wife (at the time girlfriend) moved in, we split the interest portion of the mortgage payment 50/50. Principle was 100% me. Utilities food and supplies were evenly split. Every bolted down upgrade I paid for 100%, but we decided to split paint since it mattered more to her.

The idea was if she bolted, I would mostly be left with what I paid for. If we got married (we did), we’d combine finances and it wouldn’t matter anyway.

I’d see someplace close to 50-50. Maybe you cover a little bit more because you’ll get some of the money back when she moves out.Maybe I should say if she moves out.

No matter how you do it put it in writing. Let me state that again , put it in writing. And yes, I know there are certain people who not listening or not paying attention so I’m gonna say it a third time: put it in writing.

Do not assume anything do not use verbal agreements. You will get screwed. It’s not a matter of if it’s when. You will get screwed. write everything down. Who covers what who owes what how the bills are going to be split.

Edit: and just to make a slight addition here. When I say everything I mean everything. Including how long she gets to live there for. under what circumstances and what conditions. Who owns the apartment. Everything. I don’t know about where you live, but here once a person lives in a certain place a certain period of time they are called a the resident. trying to kick them out even if you own the place is a pain in the ass. So write everything down no exceptions.

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

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.

Utilities 50/50. Look at what renting a similar place costs, and halve of that.

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.

I am not sure the way Amsterdam law sees it but in a lot of countries if shes paying some of the mortgage and she lives there for a certain length of time she becomes part owner of said condo. Best to get legal advice as if you break up you may be forced to sell and split part of the sale.

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.

Stumbled into c/relationshipmath over here

A relationship is built on trust. You are not room mates. Invite her to move in with no expectations, and let her decide how she wants to contribute.

My husband and I split things by % of income. First, we made a list of all household bills that we both benefit from - this includes everything from the mortgage to Netflix. Everything. We put it on a shared spreadsheet in Google Drive so we can both access it and update it. The sheet includes the bill description, the amount of it, the due date, and the frequency (weekly, monthly, annually), with another column to deduce the monthly cost of all bills based on frequency.

Next up we made a section for income, and totaled out what we each take home every month. This is AFTER taxes and insurance, what actually lands in the bank accounts. Then we take the total of all the bills and figure out what % it is of our total combined income. For instance if the combined income is 5000/mo and the total for all bills is 3500, then it’s 70%. Lastly, we then have a spot that determines what 70% of each of our monthly incomes are. So let’s say you bring home 3500 and she brings 1500 - in this scenario you would pay 70% of 3500, or 2450 monthly, and she would pay 1050. If you get paid twice in a month, divide that by 2 and you know what you each should contribute per pay period.

If you setup the sheet with proper formulas, you can just update the bills as needed, and change the income as needed, and it will update contributions automatically. This is the simplest version, but you can also include savings and stuff if you want as well. We opened a joint checking account separate from our main ones when we moved in together, and we transfer the money to it for bills each time we’re paid, and all bills come out of that account. Our personal accounts are kept separate and private, because anything left after bills and savings is our own money to spend or save however we like.

Personally I think this is the most equitable way of doing things. We ensure that all bills are paid and that we both have a bit of spending money. We’ve been together for 20 years, and have kept this system for most of it!

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

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