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Create
Refund a paid or overpaid invoice in full or for the overpayment difference back to the first confirmed sender address.
API key: Payment
Creates an on-chain refund for a paid or paid_over invoice within 14 days of its last confirmed deposit. Both the destination address and the refund amount are computed automatically by the server: funds return to the sender address of the first confirmed invoice deposit (first_sender), and the merchant balance is debited for amount + fee.
Request body
| Parameter | Type | Required | Description |
|---|---|---|---|
invoice_id |
string | Yes | Prefixed invoice identifier (inv_...) belonging to a project in the key's scope |
mode |
string | Yes | "full" (returns the remaining refundable invoice balance) or "overpayment" (returns only the excess over the requested invoice amount) |
external_order_id |
string | Yes | Your idempotency reference (max 200 characters), unique per merchant and environment |
Example request
{
"invoice_id": "inv_7K2M9P4Q8R1X5Z3A0bC2dE",
"mode": "full",
"external_order_id": "refund-1042-full"
}
Code examples
Each tab uses an official SDK with a Payment key (pk_). Signing, serialization, safe retries, and typed errors are handled by the SDK.
API_KEY_ID="pk_live_xxxxxxxxxxxx"
API_SECRET="sk_live_xxxxxxxxxxxx"
BODY='{"invoice_id":"inv_7K2M9P4Q8R1X5Z3A0bC2dE","mode":"full","external_order_id":"refund-1042-full"}'
TS=$(date +%s)
BODY_HASH=$(printf '%s' "$BODY" | openssl dgst -sha256 -hex | sed 's/^.* //')
SIGNATURE=$(printf '%s\n%s\n%s\n%s\n%s' "$TS" POST /v1/refunds '' "$BODY_HASH" \
| openssl dgst -sha256 -hmac "$API_SECRET" -binary | base64)
curl -sS https://api.paymos.io/v1/refunds \
-H "Authorization: HMAC-SHA256 $API_KEY_ID:$SIGNATURE" \
-H "X-Request-Timestamp: $TS" \
-H "Content-Type: application/json" \
-d "$BODY"
import { Paymos, externalOrderId } from '@paymos/sdk';
const paymos = new Paymos({
apiKey: process.env.PAYMOS_API_KEY,
apiSecret: process.env.PAYMOS_API_SECRET,
});
const refund = await paymos.refunds.create({
invoiceId: 'inv_7K2M9P4Q8R1X5Z3A0bC2dE',
mode: 'full',
externalOrderId: externalOrderId('refund'),
});
console.log(refund.withdrawalId, refund.status);
import os
from paymos import Paymos
paymos = Paymos(
api_key=os.environ["PAYMOS_API_KEY"],
api_secret=os.environ["PAYMOS_API_SECRET"],
)
refund = paymos.refunds.create(
invoice_id="inv_7K2M9P4Q8R1X5Z3A0bC2dE",
mode="full",
external_order_id="refund-1042-full",
)
print(refund["withdrawal_id"], refund["status"])
<?php
use Paymos\Client;
use Paymos\ClientConfig;
use Paymos\IdempotencyKey;
$paymos = new Client(new ClientConfig(
getenv('PAYMOS_API_KEY'),
getenv('PAYMOS_API_SECRET')
));
$refund = $paymos->refunds()->create(array(
'invoice_id' => 'inv_7K2M9P4Q8R1X5Z3A0bC2dE',
'mode' => 'full',
'external_order_id' => IdempotencyKey::externalOrderId('refund'),
));
echo $refund['withdrawal_id'] . ' ' . $refund['status'];
package main
import (
"context"
"fmt"
"os"
paymos "github.com/Paymos-labs/go-sdk/v2"
)
func main() {
client, err := paymos.NewClient(os.Getenv("PAYMOS_API_KEY"), os.Getenv("PAYMOS_API_SECRET"))
if err != nil {
panic(err)
}
refund, err := client.Refunds.Create(context.Background(), paymos.CreateRefundParams{
InvoiceID: "inv_7K2M9P4Q8R1X5Z3A0bC2dE",
Mode: paymos.RefundModeFull,
ExternalOrderID: "refund-1042-full",
})
if err != nil {
panic(err)
}
fmt.Println(refund.WithdrawalID, refund.Status)
}
using Paymos;
using var paymos = new PaymosClient(
Environment.GetEnvironmentVariable("PAYMOS_API_KEY")!,
Environment.GetEnvironmentVariable("PAYMOS_API_SECRET")!);
var refund = await paymos.Refunds.CreateAsync(new CreateRefundRequest(
InvoiceId: "inv_7K2M9P4Q8R1X5Z3A0bC2dE",
Mode: RefundMode.Full,
ExternalOrderId: "refund-1042-full"));
Console.WriteLine($"{refund.WithdrawalId} {refund.Status}");
import io.paymos.CreateRefundRequest;
import io.paymos.PaymosClient;
import io.paymos.Refund;
import io.paymos.RefundMode;
PaymosClient paymos = new PaymosClient(
System.getenv("PAYMOS_API_KEY"),
System.getenv("PAYMOS_API_SECRET"));
Refund refund = paymos.refunds.create(new CreateRefundRequest(
"inv_7K2M9P4Q8R1X5Z3A0bC2dE",
RefundMode.FULL,
"refund-1042-full"));
System.out.println(refund.withdrawalId() + " " + refund.status());
require 'paymos'
paymos = Paymos::Client.new(
api_key: ENV.fetch('PAYMOS_API_KEY'),
api_secret: ENV.fetch('PAYMOS_API_SECRET')
)
refund = paymos.refunds.create(
invoice_id: 'inv_7K2M9P4Q8R1X5Z3A0bC2dE',
mode: 'full',
external_order_id: 'refund-1042-full'
)
puts "#{refund.withdrawal_id} #{refund.status}"
use paymos::{CreateRefundRequest, PaymosClient, RefundMode};
let paymos = PaymosClient::new(
std::env::var("PAYMOS_API_KEY")?,
std::env::var("PAYMOS_API_SECRET")?,
)?;
let refund = paymos
.refunds()
.create(&CreateRefundRequest {
invoice_id: "inv_7K2M9P4Q8R1X5Z3A0bC2dE".to_owned(),
mode: RefundMode::Full,
external_order_id: "refund-1042-full".to_owned(),
})
.await?;
println!("{} {}", refund.withdrawal_id, refund.status);
Response (201 Created / 200 if idempotent match)
{
"withdrawal_id": "wdr_6Qm2fK8xR4vN7cT1bY9dL5",
"invoice_id": "inv_7K2M9P4Q8R1X5Z3A0bC2dE",
"mode": "full",
"external_order_id": "refund-1042-full",
"status": "created",
"is_final": false,
"is_test": false,
"amount": "100.00",
"fee": "1.00",
"currency": "USDT",
"network": "TRC20",
"destination_address": "TN3W4H6rK2ce4vX9YnFQHwKENnHjoxb3m9",
"first_sender": "TN3W4H6rK2ce4vX9YnFQHwKENnHjoxb3m9",
"created_at": 1767225600,
"type": "refund",
"project_id": "prj_3F9xL2mN8pQ4rT6vW1yZ5b"
}
Response fields
| Field | Type | Description |
|---|---|---|
withdrawal_id |
string | Prefixed payout identifier (wdr_...) representing this refund |
invoice_id |
string | Prefixed invoice identifier (inv_...) being refunded |
mode |
string | Refund mode: "full" or "overpayment" |
external_order_id |
string | Your idempotency reference echoed back from the create request |
status |
string | Current status (created, signed, pending_review, cancelling, completed, failed, or cancelled) |
is_final |
boolean | true once the refund reaches a terminal state (completed, failed, cancelled) |
is_test |
boolean | true for sandbox refunds |
amount |
string | Exact token amount returned to the payer |
fee |
string? | Flat per-token network payout fee charged to the merchant balance in addition to amount. Omitted when zero |
currency |
string | Crypto asset symbol (matches the invoice's payment currency) |
network |
string | Blockchain network code (matches the invoice's payment network) |
destination_address |
string | Payout destination address (always equal to first_sender) |
first_sender |
string | Canonical sender address of the first confirmed deposit on the invoice |
tx_hash |
string? | On-chain transaction hash once status is completed |
explorer_url |
string? | Block explorer link for tx_hash once status is completed |
created_at |
integer | Unix timestamp in seconds |
completed_at |
integer? | Unix timestamp in seconds when the refund completed |
failed_at |
integer? | Unix timestamp in seconds when the refund failed |
cancelled_at |
integer? | Unix timestamp in seconds when the refund was cancelled |
type |
string | Always "refund" |
project_id |
string | Prefixed project identifier (prj_...) that owns the invoice |
Idempotency
Always send a deterministic external_order_id for each refund attempt. Retrying POST /v1/refunds with the same (invoice_id, mode, external_order_id) returns the existing refund with 200 OK instead of creating a duplicate payout. Reusing an external_order_id with a different invoice_id or mode is rejected with 409 idempotency_conflict.
Only one active refund may be in flight per invoice at a time. You can issue an "overpayment" refund first and a "full" refund for the remaining principal after the overpayment refund reaches completed.
Errors
| Code | HTTP | When |
|---|---|---|
payment_key_required |
403 | The request was signed with a Payout (rk_) key instead of a Payment (pk_) key |
refunds_not_enabled |
503 | Invoice refunds are disabled in this environment |
invoice_not_found |
404 | invoice_id does not exist or is outside the API key's project scope |
refund_not_eligible |
409 | The invoice is not in paid or paid_over status, or its deposits are not eligible |
refund_no_overpayment |
409 | mode is "overpayment" and the invoice has no remaining overpayment balance |
refund_sender_unknown |
409 | The sender address of the first confirmed deposit is unavailable |
refund_window_expired |
409 | More than 14 days have passed since the invoice's last confirmed deposit |
refund_network_unsupported |
409 | Payouts are not supported on the invoice's payment network |
refund_in_flight |
409 | Another refund for this invoice is still in a non-terminal status |
invoice_already_refunded |
409 | The invoice has already been refunded in full |
refund_source_inconsistent |
409 | Invoice deposit or refund ledger history failed consistency verification |
insufficient_balance |
409 | Merchant balance cannot cover amount + fee |
See Error Codes for the full catalogue.