Hi,
I can tell you how we handled it (even if some find the following peculiar, for us a one-time and clear agreement was the method of choice).
The initial situation was somewhat different, but the status regarding the living situation (1 partner owner, 1 partner not) is identical: My ex-girlfriend and I built in 2013/2014. After 9 months, the separation happened for reasons not relevant here. As a result, she was removed from the land register, I became the sole owner, the bank cooperated and released her from the loan agreement. So, a clean break at that point.
Then I met my current girlfriend and at some point the topic of moving in together came up, along with the same question you have.
We solved this through a corresponding “Agreement on Living and Residential Partnership” with similar rules to a rental contract. (If someone comes up with this: Whether it would be legally binding in a court dispute was not relevant to us - the aim was to clearly regulate certain matters and agree on them.)
The basis for the calculation was, as already suggested here in the thread:
- half of the interest
- half of the additional costs
- half of the maintenance reserve
- (not yet mentioned) a contribution for the further development of the garden of the new building (since acquisition costs borne by me, but jointly designed and used)
Agreement on the Formation of a Living and Residential Partnership
Between
xxx
And
YYY
1. XXX is the owner of the property XXX.
2. YYY moves in as a life partner with effect from 01.12.2015, so that both parties jointly occupy the property and YYY has the right to co-use the land including all structural facilities.
3. As a contribution to the maintenance costs for the property, YYY pays a flat rate of 440€ / month to XXX. The amount is due on the 1st of each month. A change in the cost contribution is only possible by mutual agreement. Gas and electricity costs are not included in this amount and are shared equally by both parties as part of the joint household management. The amount is based on the billing from the energy suppliers. XXX remains the contractual partner with the energy suppliers. Also excluded are non-property-related living costs (e.g. internet, television, insurances except building insurance, GEZ)
4. Necessary repair and renovation work as well as value-increasing measures / new acquisitions are borne solely by XXX as owner.
5. In the event of a separation of the life partners, YYY is granted a right of residence (not obligation) for 3 months.
6. In the event of the death of XXX, YYY is granted a right of residence (no obligation) for 6 months with the agreed cost contribution to arrange the further procedure with the heirs or to move to a new accommodation.
7. If XXX contemplates a sale, YYY must be informed in good time, but at least 3 months before the sale date. In the event of dissolution of the life partnership, point 5 applies.
8. YYY expressly has the right to terminate this agreement without notice and to dissolve the living and residential partnership. The dissolution becomes effective immediately.