The ruling regarding a Dhimmi who converts after having paid a portion or all of the Jizyah for the year.

Primary text

If a Dhimmi has taken the Jizyah in his hand and then converts to Islam, it must be returned to him, according to a narration attributed to Umar. Furthermore, there is a narration from the Prophet that states: 'It is not appropriate for a Muslim to pay Kharaj' (meaning Jizyah). A Dhimmi converted and was then demanded to pay Jizyah, claiming his conversion was merely for refuge. He was told, 'There is refuge in Islam.' When this was brought before Umar, he declared, 'There is refuge in Islam,' and he wrote that Jizyah should not be taken from him.