When determining the basis of taxation, trading costs in the form of commission etc. in connection with the purchase and sale of taxable securities, real property or other commercial undertakings are, as a general rule, added to the acquisition sum or deducted from the consideration in accordance with other taxation of profit.

As a general rule, trading costs are thus not tax-deductible under Section 9 of PAL. Whether the costs are to be included in the basis of taxation depends on whether the yields from the asset is liable to taxation under PAL.

If external accounting provisions do not authorise adjusting the acquisition sum or consideration for the taxable asset by the trading costs, these can, in exceptional cases, be deducted directly in connection with the determination of the basis of taxation under Section 9 of PAL.

One example of external accounting provisions is Danish Executive Order no. 1266 of 26 October 2007 on financial reports for life insurance companies and lateral pension funds (nationwide occupational pension funds). Section 22(6) of this Executive Order stipulates that life insurance companies and lateral pension funds (nationwide occupational pension funds) must enter the costs attributable to trade with and administration of the company's investment assets in the subitem ‘Administration costs in connection with investment activity' (Administrationsomkostninger i forbindelse med investeringsvirksomhed).

Interest on deferred payments, i.e. interest paid in connection with the purchase and sale of bonds, mortgages and other claims, are treated as interest taxable under Sections 3, 6 and 7 of PAL and thus not as a trading cost.