Recommendation on declaring days of MAB action

Imperial UCU MAB declaration recommendation
You don’t declare MAB until asked, and then you must declare.
Different parts of College are handling this in different ways but one eventual outcome following a declaration is that your department informs HR, who then write you a standard message informing you of the 25% pay deduction on a certain day. Note the time lag on receiving this message following declaration is variable, and seems to take at least two weeks. 
It seems HR are sending a standard letter from their industrial action account with a line in italics in the middle that either says (a) they have noted you want pensions contributions made up, or, (b) that have not​ been informed about this yet, so please reply if want this done. With MAB, wait till this letter arrives and then reply if needed to have the pension contributions made up.