TLDR: You need a lawyer.

I think, ethically, speaking out is the right thing. Falsifying grants is despicable and has a very negative impact on science in general. It has happened to me multiple times that when I say in a pub that I am in science and that I got a grant people say things like "All those grants are just frauds to get money from the government/EU". I don't think I need to explain why this kind of perception hurts on both personal and systemic level.

Regarding your own well being, things are much more difficult. The fact is that you have willingly participated in a non-trivial fraud for a prolonged period of time. Speaking out will not erase this neither ethically nor legally.

You need to consult a lawyer (not an Internet law advice, a real lawyer). As pointed out in the comments - you may easily be considered a part of the fraud. You may want to check your country's whistleblower/cooperating defendant protection laws, but those (if existent) usually do not provide any strict protection - court will have to decide whether you will face charges. OTOH, if the scheme is revealed later without your involvement, you will be in much worse situation than if you had spoken. You may also claim to have acted in good faith or under serious threat (losing employment). Once again, a lawyer should be able to tell you to what extent this may protect you under the relevant jurisdiction, given the specific circumstances (there is no simple general rule).

Be aware, that you are in trouble. I don't think there are so many grants of this kind and much fewer of them are being cheated like the one you speak about. There is a non-negligible chance that someone overseeing the project reads this post and may consider checking whether this isn't "his" project. Some other participant of the grant may read this as well and consider speaking out himself to get into a better situation. And as this sounds like a big and ongoing fraud, it may easily burst on its own - once people get too much used to bending rules they usually do not know when to stop.

This is not a "we used a questionable accounting trick to be able to buy a new device we really needed for research" kind of problem, there is no good intent, neither was the money used in the spirit of the grant.

EDIT: One more bad scenario in response to some of the comments. Let's suppose the fraud is exposed. Even if the funding agency does not initiate a criminal investigation and even if they cannot directly claim money from you (as your contract is probably with the uni) you still have trouble. Since the uni will likely have to return a large sum of money, they can file civil suit against the people involved in the fraud seeking financial compensation for the loss. As you have made false statements about accommodation and other stuff, this can easily include you.

EDIT 2: I would like to highlight a good point made in AndrejaKo's answer: If the corruption is sufficiently deep in the system, it might not be actually possible to bust your advisor (read the answer for detailed reasoning).

Since the question is intentionally vague, I think there's one more angle that should be considered in the general case and that everyone missed: Can I actually bust my PhD adviser?

Let's be honest: Such deep level of cover-ups shows that entire operation is being conducted in a society that allows corruption, so it would be a bit naive to think it's only localized to academia.

Assuming you actually have sufficient evidence to incriminate the whole gang, can you be sure that someone is going to act on those evidence? Are you sure that none of the implicated professors have a colleague from law school who just happens to be best friends with the prosecutor to whom your case gets assigned to? Or the judge? Can you be 100% sure that your case won't spend next XX years untouched at the bottom of the stack of the cases that need to be solved?

If the behavior you're describing is being tolerated by such large number of people, can you be 100% sure that there's absolutely no government backing in it? Are you sure that people controlling the grant money are as incompetent/naive as they look and are not in fact somehow taking a percentage of the grant money for themselves? We'll give you 100 million, but you'll give me 1 million!

To put is simply, I suspect that there could be a very serious danger that you could report this to the authorities, exposing yourself in that way and burning all bridges with your research community, and at the same time have authorities do absolutely nothing about it, other than perhaps prosecuting you personally for your contribution to the plot. Such things can be common in societies with large levels of systematic corruption and in that case, by reporting the plot, you'd only exile yourself from academia. It could quite easily happen that in such case you may need to leave your country and start looking for work elsewhere.

Now, I'm not saying that you shouldn't be rocking the boat, I'm just trying to focus a little bit on the consequences part of the question. Make sure that you have a plan in place in case your attempt to expose the plot fails.

Many people recommended that you speak to a lawyer. Instead, I'll say: Try to find a good lawyer that specializes in corruption cases and can explain to you how exactly is it realistic for you to expose people and where you should report the fraud if it is in fact feasible to report it. Then find another lawyer with same qualifications and speak to him as well! Keep in mind that in busting your adviser, you'll be making a whole bunch of enemies, many of them of high rank, quite possibly for life. People say: "The wheels of justice turn slowly, but grind exceedingly fine." Even in the case that the rest of your society is not as corrupt as I fear it to be, what are you going to do while the case is being processed, which can easily take many years? Would you be able to eat and drink your honesty?

So once again, before you actually do anything, make sure you have plans in place so you are safe if it all backfires.

Warning: Harsh answer following

Let me state some facts:

• You probably took a PhD you did not deserve ("worthless" was your original wording) to satisfy the grant requirements
• You were paid unusually lots of money for a PhD student, probably without having to do TAs but working exclusively on the grant aka your research (those type of grants offer very high paychecks even for the PhD students, since they also have money for relocation, living expenses etc...). In EU, PhD students on such projects are paid as much as €2700 - €3500 per month for as much as 3 years => you probably were paid >€100k.
• You probably had a very big travel budget for conferences, with little administrative overhead (contrary to most PhD students who are on a very tight travel budget)
• You put your signature on falsified documents, probably lied in person to your grant reviews, did not resign or returned the money you falsely took when you discovered the fraud.
• Having received all that money and getting your PhD, you now have a guilty conscience and a change of heart.
• You want to do the "ethical" thing but without voluntarily returning all the money you received from the grant.

Somehow, I cannot see you as a victim here.

As far as I am concerned, consulting a lawyer and voluntarily returning all the money you illegally received from the grant (after consulting your lawyer) are the only viable solutions if you want to come clean.

First, consider the seriousness of the situation. The grant was supposed to fund real exchanges, but the paperwork suggests those exchanges never happened. This could be a violation of federal or state regulations, university policy, and possibly criminal law. Reporting it is generally the right ethical choice, but you should proceed carefully to protect both your academic record and your future career. **Gather what you can.** - Keep copies of any documents you saw (meeting minutes, emails, grant reports) and note dates, names, and the claims made. - Talk to any fellow students or post‑docs who may have similar recollections. Even if they are hesitant, a shared account strengthens the case. **Use internal channels first.** - Most universities have a research compliance office, an office of sponsored programs, or an ethics hotline. Submit a confidential report there, describing the facts without speculation. - Ask for guidance on how to document your concerns and whether you can remain anonymous. **Consider the consequences.** - **For the advisor and institution:** Falsifying grant reports can lead to funding repayment, sanctions, loss of eligibility for future grants, and possible criminal charges. - **For you:** Whistleblower protections exist under federal law (e.g., the False Claims Act) and many state statutes. You may be shielded from retaliation such as termination, demotion, or loss of recommendation letters. However, retaliation can still occur, so document any adverse actions promptly. - **Professional reputation:** Reporting misconduct can be viewed positively by future employers and funding agencies, especially if you follow proper channels and maintain professionalism. **Next steps.** 1. Contact your university’s compliance or research office. 2. Request advice on how to file a report and what protections are available. 3. If you feel unsafe or see no response, consider contacting the granting agency’s inspector general or a relevant government oversight body. By acting through official channels, you help ensure accountability while minimizing personal risk.