The IMO is expensive to run but, of course, we believe it is very worthwhile. If you have benefited from IMO, or would like to support us, you might consider making a donation to the IMO Foundation. This is a charitable organisation (for tax purposes) whose sole purpose is to support the work of the IMO, primarily through subsidising host nations who take on the event. We also sponsor guest mathematicians who give lectures to participants.
Your contribution, great or small, will be appreciated by future generations of IMO participants. All donations will be receipted and acknowledged on the donor register (unless you choose to remain anonymous).
Countries or national Olympiad organisations making contributions in response to the request of the IMO Advisory Board should open the pdf for detailed instructions