When you void a label within SKULabs, we submit a refund request for the postage, label creation price, and any insurance purchased through your carrier.
Each carrier has their own policies regarding refunds and you should consult your carrier.
FedEx and UPS labels are typically bill-on-scan but confirm with your representative.
USPS labels must usually be voided within 24 hours of creation and take about 30 days before they are refunded–usually as account credit with whichever USPS integration partner you're using. Also see more on USPS's New Policy on invalid shipping labels
See EasyPost's documentation on refunded labels:
See Shippo's documentation on refunded labels: