Both Stamps.com and ShipStation Carrier Services give you control over your postage balance within the ShipStation app. You can add funds to your balance manually or set it to automatically add funds once it reaches a specified threshold.
Click the Add Funds link next to your Stamps account.
Next, you can manually add funds to your balance, or set ShipStation to auto-fund your balance when it falls below a certain threshold.
Manually add funds:
Select the option Manually purchase additional funds, then enter the funding amount.
Set ShipStation to auto-fund:
Select the option Set up Auto-Funding, then enter the balance amount to trigger the auto-fund purchase, the amount to fund, and the maximum number of times the auto-fund can occur each day.
For example, if you wanted to purchase $100 by default any time your account balance falls below $250, set the When balance drops below amount to 250 and the Automatically fund by this amount to 100. Then enter in the maximum number of times ShipStation should automatically purchase postage in a day next to Stop after this many times per day.
This feature triggers ShipStation to add funds when ShipStation detects the Stamps.com account has fallen under a certain threshold and is not connected to Stamps.com's own Auto-buy postage feature that can be enabled when logged into Stamps.com directly. We recommend you only have auto-funding enabled in one location, as having the feature enabled in both ShipStation and Stamps.com can cause funds to be added twice.
Stamps requires a minimum purchase of $10.