(1) If the lessee is to provide to the lessor a security deposit for the performance of their duties, then this security deposit, subject to subsection (3) sentence 4, may amount at most to three times the rent for one month, exclusive of the operating costs shown as a lump sum or as an advance payment.
(2) If security is to be provided in the form of a sum of money, then the lessee is entitled to pay in three equal monthly instalments. The first instalment is due upon commencement of the lease. The further instalments are due together with the immediately ensuing rent payments.
(3) The lessor is to invest a sum of money made available to them as a deposit with a banking institution at the usual rate of interest for savings deposits to which a withdrawal notice of three months applies. The contractual parties may agree on another form of investment. In either case, the investment must be made separately from the assets of the lessor and the lessee is entitled to the income. It accrues to the security deposit. For residential space in a student hostel or a hostel for young people, there is no duty for the lessor to pay interest on the security deposit.
(4) A deviating agreement to the disadvantage of the lessee is ineffective.