https://www.kidneyregistry.com/for-donors/kidney-donation-blog/taking-time-off-work-to-donate-a-kidney/

"The Family and Medical Leave Act (FMLA) is a federal law that allows eligible employees to take up to 12 weeks of unpaid leave annually for specific family or medical reasons, including organ donation. During FMLA leave, your job is protected, and your employer must maintain your group health insurance. In general, to qualify for FMLA, you must work for a company with at least 50 employees and have worked for the company for at least one year."