17 Trade and other payables
| | 2018 | 2017 |
Trade payables | 2,460 | 826 |
Rent invoiced in advance | 5,248 | 5,074 |
Group companies Bouwinvest | - | 1,627 |
Tenant deposits | 1,068 | 884 |
Service charge payments | 441 | 566 |
Promotion costs | 226 | 167 |
Tax | 75 | 67 |
Other payables | 2,098 | 708 |
Balance as at 31 December | 11,616 | 9,919 |
The other payables relate to invoices yet to be received for maintenance of and investments in the portfolio.