Stative verbs are not used in Continuous Tenses.
Some of the stative verbs are: Agree, Believe, Belong, Hate, Like, Know, Prefer, Remember, Smell, Sound, Taste etc.
Example: The car that he is using / these days is belonging / to his employer. / No error
Explanation: Belong is a stative verb; so the sentence should not be in continuous tense. Therefore, there is an error in the second part of the sentence; ‘is belonging’ should be replaced by ‘belong’.
Hence, the correct sentence should be:
The car that he is using these days belongs to his employer.