When on secondment, the ITN fellow continues to be paid by the recruiting beneficiariy. The country correction coefficient used to caculate the living allowance does not change. The costs of participation in the secondment cannot not be paid by the fellow; the additional costs of the fellow, such as short term accommodation costs and travel costs can be covered by category Research, Training and Networking costs. In terms of the research costs, in the financial report cost claim (Form C), the unit cost should always be claimed by the beneficiary paying the fellow, but costs can be transferred within the network subject to agreement between the beneficiaries.
In the case of a long-term secondment (e.g. 1 year), the fellow should not pay double rents and could use the mobility allowance to pay it. So accommodation in this case is covered by the mobility allowance.
The MSCA explained by your National Contact Points