27. EXTERNAL SUPPLIES AND SERVICES

The caption “External supplies and services” for the years ended 31 December 2014 and 2013 is made up as follows:

'14

'13

Maintenance costs

12.168

10.507
Fees relating to external entities i)

8.919

10.809
Electric energy costs

4.179

4.555
Insurance costs

2.989

2.816
Gas transport subcontracts

2.959

2.849
Security and surveillance

1.659

1.757
Advertisement and communication costs

1.280

1.616
Cross border interconnection costs ii)

766

1.573
Reserve capacity costs

-

1.359
Other (less than 1,000 thousand Euros)

5.618

6.185
External supplies and services

40.537

44.028

i) The fees paid to external entities refer to specialized work and fees paid by REN for contracted services and specialized studies.

ii) The cross border interconnection costs refer to the cost assumed on cross-border trade in electricity. The decrease in the period ended 31 December 2014, when compared with the same period of last year reflects the reduction of the flows of electricity imported.

This caption includes financial statements audit services as well as consulting services rendered by audit companies recorded as expenses in 2014, as follows:

'14

'13

Audit and revision of accounts

336

276
Other services of reliability guarantee

77

106
Tax consultancy services

8

17
Services other than the legal review of accounts

77

106

497

505