Not sure if this has already been covered, but I have a question about how the Arrival+ card works with regard to redeeming arrival miles for charges.

Barclays says I can redeem for any travel related charges from the past 120 days. If I redeem points for a charge though from a previous statement that I've already paid off, how does that work then when I redeem points? Does my account go into a negative balance if I don't have any recent charges since my statement closed?