its inside right now because its too cold, going out soon

Those leave look like the tree is extracting nutrients from before dropping them. Most of them are older and ready to drop. What kind of kumquat is it. Meiwas are the hardest to grow.

I have no idea, how can u udentify it?

i a pretty sure it is fortunella japonica, it was an impulse buy from a lowes

Nagam's are the only kumquat findable at big box stores. They are easy to graft and grow on any rootstock. Kumquats are not particularly easy to grow but are quite manageable

This is mine after losing 1/4 of leaves .

It has yellow veining leaves that have since dropped.

is that dirt or media the plant is in ...

has the media failed.. when was the last time it was changed ..

how do you water.. does water flow freely thru the media???

you havent given us much to think about.. other than a few yellow leaves ..

is is not uncommon for plants to shed some leaves in winter.. so it might all be normal ... or within normal limits as they might say ...

you said you brought it in because it got to cold outside.. could it have been cold damaged before you brought it in???

ken

It came in before any hard frost and has lost the expected amount of leaves. It is potted in 5-1-1 mix in the bottom 1/3 followed by 4-2-1 in the top 2/3. The mix is 1.5 years old freshly made. It will get transplanted in about a year with a new similar mix. I soak the plant every month to insure total saturation and water when needed between soakings. Just showing that winter leaf drop is normal when growing out of zone.