Within the framework of a specific assessment of needs, the need for maintenance appropriate to the marriage in the case of separation maintenance is to be determined on the basis of the costs required to maintain the standard of living achieved in the marriage.
The concrete housing need is to be determined by ascertaining what amount the person entitled to maintenance would have to pay as a tenant for an appropriately sized apartment corresponding to the standard of the marital home.
Maintenance is also limited in the concrete assessment of needs by the principle of halving. As in the case of quota maintenance, half of the maintenance is therefore the upper limit for the concrete assessment of needs.

BGH, 29.09.2021, XII ZB 474/20