We strongly recommend that you send a miner fee with your bitcoin payment. Miner fees are given to the bitcoin miner that appends the transaction to the Bitcoin or Bitcoin Cash blockchain. These miner fees are not BitPay fees, but they do increase the likelihood that your transaction will confirm more quickly.
A simple way to ensure that your transaction includes an appropriate fee is to adjust your wallet settings to include a dynamically-calculated fee. The BitPay wallet includes this setting option, which will help ensure that your transaction confirms, even at times of high network traffic.
When you pay a BitPay invoice, your payment goes to a BitPay address. We pay network-based miner fees (just like you pay to send BTC or BCH) to move invoice payments so we can combine them for processing in something called a "UTXO sweep" (Unspent Transaction Output sweep).
Miner fees are variable costs for BitPay based on network conditions. This means the Network Cost fee also changes to reflect network conditions. Read our original post about why we introduced the Network Cost in February 2017.
BitPay uses this fee for the UTXO sweep, so it is not returned with refunds.
BitPay charges a 1% processing fee to BitPay merchants. Merchants may choose to pass this fee on to the buyer.
Refund Miner Fee Cost
If you underpay or overpay a BitPay invoice and initiate a refund to yourself, BitPay will deduct the miner fee cost of returning the payment from the total refund amount you receive.
If you are a BitPay merchant and issue a full refund to your customer, BitPay will deduct the miner fee amount from your merchant ledger balance. The deduction will be a separate entry in your BitPay ledger after we execute the refund.