7 Property operating expenses
| | 2018 | 2017 |
Taxes | 1,859 | 1,872 |
Insurance | 166 | 163 |
Maintenance | 1,441 | 1,428 |
Valuation fees | 167 | 159 |
Property management fees | 935 | 898 |
Promotion and marketing | 493 | 273 |
Letting and lease renewal fees | 961 | 686 |
Other operating expenses | 1,590 | 1,375 |
Addition to provision for bad debts | 446 | 40 |
Total property operating expenses | 8,058 | 6,894 |
In 2018, € 0.2 million (2017: € 0.2 million) of the maintenance expenses related to unlet properties.