Tax implications of the small business mutual aid prepayment refund/income

After paying this year's small business mutual aid premium I received a small transfer from them. Apparently you get a certain amount back for prepaying, and once that adds up to over ¥5000 they send it to you.

For income tax purposes do I need to deduct this from my small business mutual aid payment amount for this year? Or is it some other kind of income, or what?