It is the individual taxpayer that have to determine the amount of taxable gain or deductable loss when compelting a taxable sale of property. If you do not determines the gain or loss in the tax return, the tax office determines the amount of gain or loss.

Gains on the sale of plots are always taxable. Taxable gains form part of general income and are taxed at the rate of 25 percent for the income year 2016, and 24 percent for the income year 2017. In principle, any gain made on the sale or other realisation of housing is liable to tax. However, there are extensive exemptions from the obligation to pay tax based on rules about period of ownership and occupancy, that give exemtion for gains. Losses on a sale are only deductible in cases where any gain would have been taxable. 

Even if the gain made on the sale of a house/apartment or holiday home is exempt from any tax obligation, a proportion of the fee may still be taxable under the rules concerning tax obligation upon the sale of plots.

If you use part of the property as a home office in connection with paid work, you will also be considered to have occupied this part of the home. For a salary recipient, a home office is therefore of no significance as regards the question of taxable gain or deduction entitlement for loss upon the sale of the property.  

Self-employed persons who have a home office are not considered to occupy the part of the property that is used for commercial activity. When the property is sold, tax must therefore be paid on the proportionate part of the gain which relates to the home office.