IF: How are the costs of the recruited researcher calculated?

See Art. 6.2.A(c) of the grant agreement: "Costs for the recruited researcher (A.1 Living allowance, A.2 Mobility allowance and A.3 Family allowance)"
The remuneration is the salary, social security contributions, taxes etc.; then the mobility allowance, plus the family allowance, with all three elements constituting the costs of the beneficiary of hiring the person. Therefore, in principle the living allowance is the gross salary from which to deduct social security contributions, taxes etc. to arrive at the net salary. However, in practice it depends on the tax system in every country what will constitute the gross salary and what will be taxed - in some Member States/Associated Countries, the mobility and family allowance are automatically considered as taxable salary.