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Payment Errors

Buyer Flow Edge Cases

Underpayments, overpayments, and refunds — handled clearly.

Not every invoice ends with a clean completed status. A buyer might send too little, too much, or too late. This page walks through how CoinPayments classifies each scenario and what options you have as a merchant (plus what the buyer sees on the other side).
Jump to refundsPayment timeout

Three scenarios at a glance

Pick one to jump to its detail
Underpayment
Buyer sent too little
The invoice total wasn't fully covered — usually network fees weren't included or the buyer typed the wrong amount.
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Overpayment
Buyer sent too much
The invoice closes successfully and the excess is automatically refunded to the buyer.
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Late · Stale
Sent or confirmed after timeout
The rate-lock window closed before the funds confirmed. The buyer is automatically eligible for a refund.
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Vocabulary

Shared definitions
  • Invoice

    A payment instance — the total requested, plus optional metadata like items, quantities, and descriptions.

  • Underpayment

    A payment smaller than the invoice total. A common cause: the buyer forgot to include the on-chain network fee on top of the displayed crypto amount.

  • Overpayment

    A payment larger than the invoice total. The invoice completes; the excess kicks off an automatic refund — unless the excess is smaller than network fees.

  • Payment Timeout

    The 60-minute exchange-rate lock on a checkout. After it expires, the invoice is timedOut and late funds trigger the automatic refund flow. Payment Timeout has the full lifecycle.

Automatic refunds

When CoinPayments returns funds to the buyer
Triggered automatically when…
  • The buyer sent more than the invoice total (overpayment).
  • The buyer underpaid and the payment timeout has expired.
  • Funds arrived after the timeout, or arrived in-window but didn't confirm in time.

Network fees set the refund floor

A refund won't be issued if the excess (for an overpayment) is smaller than the network fee required to send it on-chain. The dust would be consumed entirely by the broadcast cost.

Claiming a refund

What the buyer goes through
Step 1"New Refund Available" email
CoinPayments emails the buyer from do-not-reply@coinpayments.net with a unique claim link.
New Refund Available email from CoinPayments
Step 2Click "Claim Refund"
The link opens the Claim Refund window in a browser.
Step 3Provide a wallet address
The buyer enters the wallet address where the refund should be delivered. Must match the chain of the original payment.
Refund wallet address entry form
Step 4Claim the funds
The buyer confirms and the refund is broadcast. Standard on-chain confirmation depths apply before the funds arrive.
Refund claim confirmation screen

Network fees deducted from the refund

Refunds are subject to the chain's standard transaction fee, which is deducted from the refunded amount before it's sent. The buyer receives the excess minus that fee.

Underpayments

The buyer sent less than the invoice total
An invoice is only marked completed once the requested crypto amount and the required network fees are covered. The fiat equivalent shown on the checkout does not include the network fee — buyers should pay using the crypto amount field. Underpaid invoices show as Partially Paid on the dashboard.
Partially Paid status on the transactions list

Merchant resolution

Two ways to accept what arrived
Option AConfigure an underpayment limit globally

Auto-accept underpaid invoices that fall within a tolerance you set. Useful when you'd rather take a slight short-pay than lose the sale entirely.

Step 1Open Payment Settings
The same screen where you configure settlement modes per currency — see Payment Settings for context.
Step 2Configure an underpayment limit
Set the threshold as a fixed amount, a percentage of the invoice total, or both. If both are set, the smaller value wins when an underpayment is received.
Underpayment limit configuration controls
Option BAccept a single partial payment manually

One-off acceptance — leave the tolerance setting at zero and approve specific underpayments by hand from the dashboard.

Step 1Find the underpaid transaction
Open Payment Settings, locate the transaction in the list, and expand its details.
Step 2Accept the partial payment
Click "Accept Partial Payment" on the expanded row. The invoice transitions to completed and the merchant balance is credited with what arrived.
Accept Partial Payment action on a transaction row

If both limit fields are set, the smaller wins

Configuring both a fixed amount and a percentage tolerance is fine — when an underpayment arrives, CoinPayments enforces whichever value is smaller in crypto-equivalent terms.

Client resolution

The buyer's options when underpayment isn't accepted
  • Ask the merchant to accept the short payment

    A direct ask. If the merchant agrees, they accept the partial payment from the dashboard.

  • Pay the remaining balance

    The buyer can top up by reviewing the checkout window and sending the remainder in the same cryptocurrency. Switching currencies forces sending the full new amount and refunding the original — keep to the same chain.

  • Accept the automatic refund

    If the invoice ends up unpaid, the auto-refund flow returns the funds via the standard claim email.

Overpayments

The buyer sent more than the invoice total

When the buyer overpays, the invoice still completes and you receive exactly the requested amount in your merchant balance. The excess is routed into the automatic refund flow on the buyer's side — they receive the standard "New Refund Available" email and claim it the same way as any other refund.

See the refund claim flow for the buyer-side steps.

Where to next?

Pick the most useful next step.

Payment Timeout
The 60-minute rate-lock window and how it expires.
Invoice Statuses
How underpaid, completed, and timedOut fit in the lifecycle.