In Germany, the maintenance fee is transferred on a monthly basis
to the property administration. If your property is let, then the
rent is considered as income from rent and leasing according to German tax law.
As is customary for most income types, it is possible to deduct
income-related expenses. However, according to tax law the payments
for the maintenance reserve fund do not count as income-related expenses
in the moment of the cashflow. They may be deducted, once the
property administration spends the maintenance reserve fund on actual
repairs. The deduction as income-related expenses may be performed
proportionate in case. If you need more details, a tax accountant
might be able to provide you with proper advice.