Issue solved
The answer to the question is certainly different depending on who you ask. However I think I finally solved the issue. I write here my solution so everybody with the same problem can deal with it.
After talking with:
- the MSCA EU contact point: http://www.kowi.de/kowi/marie-s-curie/individualfoerderung/individual-fellowships.aspx
- the finance department of TUM
- EU officer
This is the final solution:
The secondment allowance costs must be paid from the chair as the Reisekostenstelle doesn’t pay it out. This is because they treat the stay as a secondment (“Abordnung”) and not as a “Dienstreise”.
The reimbursement must be made from the RTN unit costs (“RTN Pauschale”) which is part of the institutional unit cost of the chair.
Thus, the chair directly pays it through the MSCA Research and training costs of your project, not through the Reisekostenstelle.
Hopefully, this entry helps for future missunderstandings.
Thanks a lot to all the people that contact me to provide me information.
Best,