There is no sense in making a scene in a meeting or confronting your colleague in the hallway. If you’re emotionally piqued at being ripped off, it’s not the time to talk about it. 
Neurologically your mind is not working at its best and you may get out-argued. Take a day or two to calm down. But don’t stew about it for so long that, by the time you talk to the person, you’re ready to explode. You also want to make sure the incident is still fresh in everyone’s mind.

Take Time to Calm Down

If none of the above works and you feel like you’re being systematically undermined by the credit-stealer, you can talk to your boss or another manager who has the ability to do something about it. 
Be careful not to come off as a complainer. Frame it as an effort to create a good working relationship, not a way to badmouth your colleague. Your boss wants you to be able to work well together, not to engage in fights.

When The Problem Doesn’t Go Away

If you’re generous and intentional about sharing credit, others are likely to follow suit. 
Never hesitate to ask your team: What’s the best way to make sure all of our work is recognized?

Model Good Credit Sharing

Not every piece of work has to have your name on it and managers often take credit for the work of their subordinates. 
Making your boss shine is part of the gig. You may not get credit for the idea or for slaving over the analysis, but hopefully your boss absorbs that you’re an important part of her team.

Assess the Severity of the Situation

We want to believe that our work speaks for itself. But in the real world, it matters who gets the credit.
With collaborative work, it’s not always clear who has done what, which leaves the door open for a colleague to take undue credit.

Things Get Murkier In  Collaborative Work

Instead of making accusations, ask questions. This shifts the burden of proof to your colleague: he has to explain why he felt justified taking credit for the project or idea.Research shows that it’s much better to ask why it happened than to make a claim.Your goal isn’t to pin blame but to show them that you noticed and that you didn’t think it was right.

Ask Why

If the credit-stealer acknowledges his mistake, talk about how you can make things right. Perhaps he can email the group thanking you for your contributions, or you can both go talk to your manager to set the record straight. Even if he’s not willing to do anything, you can take action. Use any opportunity to demonstrate your involvement with the project.You might approach your colleague and say: I worked really hard on this report but sometimes find it hard to promote my own work. I would appreciate it if you asked me questions about it at the meeting.

Remedy The Situation

In collaborative projects, it’s important to agree on upfront on how credit will be allocated. Who will present these ideas to the senior team? Who will field questions? Who will send the email to the rest of the company? At the same time, people need to be able to revisit these agreements if the expected proportion of contributions changes, so be flexible.

Be Proactive About Preventing It Next Time

Do:<ul><li>Give yourself time to calm down and assess the situation</li><li>Be clear about your contributions whenever you get an opportunity</li><li>Ask colleagues to mention your name when the idea or project comes up in conversation</li></ul>Don’t:<ul><li>Feel like you need to get credit for every single thing you do</li><li>Presume that the person had malicious intentions ­— credit stealing is often an accident</li><li>Make any accusations ­— instead, ask the person questions to try to figure out why it happened</li></ul>

When The Problem Doesn’t Go Away

Similar ideas to When The Problem Doesn’t Go Away

The People You Respect

The Problem with Current Model

Your belief in the long run isn't enough