Since it's difficult to estimate the costs relating to letting when the property is also used by you, a so-called standard deduction for costs is granted instead. The standard deduction is 15% of rental income, which means that only 85% of the rental income exceeding NOK 10,000 is counted as tax liable income.

It's only when letting so-called rental cabins, where the entire rental income is taxed, that you can deduct costs incurred when letting.