In the Determination of profits werden den Erträgen die Aufwendungen oder Betriebsausgaben gegenübergestellt. Betriebsausgaben sind nach § 4 IV EStG Aufwendungen, die durch den business veranlasst sind. Dazu zählen auch die Fremdkapitalzinsen, soweit das Kapital dem Betrieb zur Verfügung gestellt wird.
With the account-based separation of a current account into an operating income account and an operating expenses account (two-account model), the non-deductibility of private debt interest is avoided. The operating income is collected in an account, from which private debts in particular are paid. The operating expenses are paid from another account.
As a result, the operational debt level increases on the expenditure account. Since this account finances operational tasks, the resulting debt interest is also deductible as business expenses; a debt interest deduction is possible. The BFH justified the tax recognition of the two-account model in 1997 with the principle of freedom of financing. With the Tax Relief Act 1999/2000/2002, multi-account models were restricted again (Section 4 IVa EStG, Section 9 V EStG). The interest rate scale method is used in its place.
The new regulation must be viewed critically, as it is incompatible with the principle of freedom of financing and violates the net principle. A change to § 4 IVa EStG took place in the StBereinG with the extension of the regulation to cash accounts, the waiver of a mandatory application of the interest rate scale method, as well as the repeal of the trivial regulation of § 4 IVa No. 4 EStG. What is missing is a specific inducement principle for the liabilities side and a consideration of the capital structure (equity and debt).