https://www.forbes.com/sites/niallmccarthy/2020/04/08/which-countries-are-the-biggest-financial-contributors-to-the-world-health-organization-infographic/#6dbb96fe494c
" In its most recent budget proposal in February, the Trump administration requested a reduction in U.S. financial contributions to the WHO from $122.6m to an assessed contribution of $57.9m. Despite the slashed budget, that figure still makes the U.S. the WHO's top financial contributor by far. China pays in the second highest sum, $28.6m, followed by Japan's $20.5m. The total sum of assessed contributions invoiced by the WHO on January 01 and due for payment this year stood at $246.8 million, of which $79 million had been paid by members as of March 31. "
This is for 'assessed contributions', which are effectively the membership fees. Over and above this there are voluntary contributions, which may be for specific projects or programs, and make up the larger part of WHO spending.