All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
If the situation is as you mentioned in the question, that the salary of your husband is not sufficient for him and the people he is obliged to provide for after paying the rent, but when adding the extra money he got (300,000) to what remains from his salary, it becomes sufficient for him to sustain himself, then in our view it is not permissible to pay the Zakat to him. This is because he fulfils his needs and the needs of whoever he is obliged to spend on with the entire money which he has, so he should not be given money as a poor or destitute person.
According to the majority of scholars the amount of sufficiency which prevents a person from being eligible to take Zakat is food and drinks and accommodation, and other necessities, either for the person himself or for those he is obliged to spend on (without being extravagant or stingy) as clarified in the Fiqh Encyclopaedia.
Living in a rented accommodation does not mean that he is poor, as long as his salary and the added money which he got are sufficient for him to pay rent, and eat and drink.
For more benefit on the recipients of Zakat, please refer to Fatwa 88368.