If a company is operating a business eligible for tax deduction as well as another business not eligible for tax deduction, how is the income of the business sectors divided?

According to relevant laws, if a company is operating both, two business sectors eligible as well as not eligible for tax deduction, then the accounting has to be done separately.

Common profits and losses have to be calculated proportionally as described below:
– The common profits have to be calculated proportionally to the income or sales amount
of the two business sectors.
– Common losses have to be calculated in proportion to the respective income or sales
amount, if the two business sectors belong to the same industry. If they are in
different industries, the losses have to be calculated in proportion to the individual
losses of each industry.