I am an executive assistant to a VP and also report to 3 of his managers. One of his managers is constantly forgetting his deadlines even when I remind him of things or telling me one thing, realizing his mistake, and then throwing me under the bus on conference calls i.e. "Oh, sorry you don't have that report, I told her to do this" etc.

It has happened on several ocassions and I haven't said anything because I don't want to look like a whiner but my boss overhears him saying these things and I don't want it to impact a performance review, promotion consideration, transfer etc. I'm not a slacker and that's how he makes me look to others when it's really him that's slacking!

I can never directly address this with the manager because he never directly addresses it with me - because he knows I did nothing wrong - I just constantly overhear him. It seems awkward and childish for me to storm to his office and correct him. I just don't want my boss thinking I'm a poor performer.

How would you handle this?

Document! Document! Document!
Do not speak with this manager unless it is via email or something you can note down.
If it's in a conference call, pretend like it's an innocent mistake on his part. Say things like, "You must have spoken with someone else about that. I will get that report to you today."

The manager believes he can get away with blaming you for his own mistakes. If he knows that you are organized, and can pull up the evidence that he made a mistake - he's a lot more likely to blame someone else.

I agree with Vintage. Document and document some more! It's a pain, extra work for you, no doubt, but it's the best thing for you to do. If you have a conversation in passing with your manager or anyone else's manager, follow up instructions or important points via email. Don't leave it up to your manager or anyone else to have your back. Management has management's back, so protect yourself...if you want to keep your job and have a good work history.

Thirded on the document. When you are reminding him of deadlines, send those reminders to him via e-mail and cc that manager's admin or whomever. That way, there's a paper trail that leads to a third-party.

it's quite common to blame some kind of "technicality" on someone when things not got done.
but if i were you when i send reminder emails...i would copy the big boss.

one time...my boss (i no longer work there) threw me under the bus in a meeting....the client, the contractor....they all knew what's going on and they all looked a little shocked...later on the client was extra nice to me (i could tell he made an effort)...he felt sorry for me....