In 1996 was signed Interim Memorandum of Understanding for ATLAS experiment (period two years 1996-1997) and in July 1998 was prepared Memorandum of Understanding (MoU) for ATLAS experiment up to 2005, which was signed by Minister of education of Slovak republic at November 26th, 2002. These two acts represent the basic juridical background for our present activities in ATLAS experiment. According to MoU of the ATLAS experiment, our financial obligations during whole time period of the detector construction are following: core expenses: 100 000,- CHF core expenses expressed as in-kind invoices: 100 000,- CHF hardware contribution into liquid argon subdetectors, especially into the construction of the hadronic end-cap calorimeter: 304 000,- CHF The proposal and the development of the calibration system for HEC calorimeter is serious and difficult task. We would like to stress that all our finance responsibilities had been fulfilled at the end of 2004. The finance policy of the ATLAS collaboration is administered by the LHC Resource Review Board - ATLAS, where Slovakia has one regular member from our Ministry of education.