Is the reputation bonus retroactive?

Certain powers, like Assault Mastery for Vanguards, give a reputation bonus to Shepard.

How exactly does this reputation bonus work? Does it just increase my total reputation by that amount, or does it work only on my future reputation gains? I'm mainly wondering whether it's necessary to get this skill as fast as possible to gain the most from it.

Solution 1:

It increases your total rep, I made this picture to show how much it can affect it has when you have 20% increased Reputation Bonus.

It works retroactively.

Solution 2:

The passive skills do not affect rep gain, just the total reputation of Shepard.

They also work retroactively. Just think about what would happen they weren't - you'd lose a sizable portion of rep every time you respec'ed, with no way to get it back.

Solution 3:

Yes, I believe it is retroactive. You will get it in the futqure, but the time you get it doesn't matter as it will scale up your current rep as well. If you respec, you will have less rep.