Is it permissible to delay fasting as an expiation for accidental killing, despite being able to perform it, until the winter season?

Scholars differed regarding the immediacy of expiation (kaffarah (definition)): whether it must be performed immediately or can be delayed. Some held that it is immediately obligatory for the transgressor, but can be delayed for the excused (like the expiation for accidental killing). Others maintained that it must be paid immediately and cannot be delayed except for a valid excuse, based on the principle that religious commands must be executed promptly. They cited the example of expiation for accidental killing: if fasting is difficult for the responsible person in summer, it is permissible to delay it until winter. If he dies before then, he incurs no sin, and either fasting is performed on his behalf or food is given from his estate.