You can freeze whole kumquats and they will keep in the freezer for 6 months to a year and sometimes longer.
But the longer the whole Kumquats remain frozen the less fresh they get and the less tasty they get as well so if you want to have the best taste and freshness from your Kumquats it's best to eat them before a few months.
But you can keep whole Kumquats frozen for a long time.
If you cut the Kumquats in halves they will stay fresher longer in the freezer which is recommended.
But if you want to just place the whole Kumquats in the freezer you can do so.
Kumquats are the healthiest when you eat them fresh but they still retain vitamins and nutrients even after they have been frozen and are still healthy for you.