All Actions: Is VAT eligible in MSCA projects only if it is not deductible for an institution as it is the case for the whole H2020?

The MSCA Model Grant Agreement does not mention VAT at all – not even once. For the unit costs to be eligible, the units have to be eligible. 

In general for Horizon2020: VAT is not an eligible cost in Horizon2020, only if the participant in the project is not entitled to deduct input tax.