SE: How many days is one month of secondment in Staff Exchanges?

It is either a full month (for example, the entire month of February), or for partial months, a pro rata calculation based on 30 days. An explanation can be found in the MSCA Financial Guidelines.

SE: What is the approach for calculating partial months of recruitment/ secondment in MSCA Staff Exchanges?

Under Horizon Europe, the approach followed for partial months of recruitment/ secondment for MSCA Staff Exchanges remains the same as in Horizon 2020. Each month consists of 30 days for the pro-rata unit calculation.