Glossary · payments and processing
What is an underpayment?
An underpayment is a crypto payment that arrives for less than the invoiced amount. It is common, usually accidental, and how a provider handles it is one of the more revealing differences between them.
Why it happens so often
Three causes, in rough order of frequency. The shopper subtracted the network fee from the amount instead of adding it. The rate moved between the quote and the send on a volatile asset. Or they simply typed the wrong number.
None of these is fraud, which is why treating an underpaid order as a failed one annoys honest customers. The useful question is how much shortfall you are willing to absorb to complete the sale.
At CoinGate that is a setting called Underpaid Cover, configurable between 0% and 10% and set separately for each merchant tool. Inside your tolerance the order completes and you absorb the difference. Outside it, the order stays open and the shopper can top up the same invoice.
One condition matters more than the percentage: the short payment also has to arrive inside the 20 minute payment window. A payment that is both short and late does not auto-complete.
How to set it
Three considerations, and none of them is a number we can give you.
Weigh it against your margin
Cover is a cost you accept to complete a sale. On thin margins a low percentage makes sense, on high margins a generous one usually pays.
Frequently asked questions
Is there an underpaid order status?
No, and this surprises integrators. Underpayment is carried as an amount on the order rather than as a state, which is also why a change in it does not fire a callback. Poll the order for that value.
Can the shopper top up?
Yes, on the same invoice, until it expires. You do not have to create a new order.
What is a sensible Underpaid Cover value?
No source we have states a typical or recommended figure, so we will not invent one. It is a margin decision. The range is 0% to 10%.
What happens to the shortfall if the order completes?
You receive the amount that arrived. Whether a fee applies on the covered difference is not documented in any source we have, so ask before you model it.