1. Category 1 Decline Reattempt Protection Save $0.10 per declined reattempt

What is this service?

Category 1 Decline Reattempt Protection prevents you from wasting money on transactions that will never succeed. When a credit card or bank account transaction is declined by the card network or bank, the decline comes with a specific reason code. Some of these reason codes indicate permanent problems that will never be resolved by simply trying again—for example, a lost or stolen card, a closed account, or an invalid card number.

Despite this, many payment systems automatically retry failed transactions multiple times, hoping they'll eventually go through. Every retry attempt costs money in processing fees (typically $0.10 or more per attempt), even though the transaction will never succeed. This service intelligently identifies these "Category 1" declines and prevents wasteful retry attempts.

How It Works

When you submit a transaction, the payment processor returns a decline code if the transaction cannot be completed. Category 1 Decline Reattempt Protection analyzes this code and categorizes it:

Response Information

When Category 1 Decline Reattempt Protection identifies a permanent decline, the transaction response includes:

Field	Description	Example Value
declineCategory	The category of decline (1 = do not retry, 2 = may retry)	"1" or "2"
declineCategoryDescription	Human-readable explanation of the category	"Do Not Retry - Permanent Decline"
responseCode	Original decline code from the processor	"14" (Invalid Card Number)
responseMessage	Description of why the transaction was declined	"Invalid card number"

Benefits

Comparison: With vs. Without Protection

Scenario	Without Protection	With Protection
Expired card is declined	System retries 3 times over 3 days Cost: 3 × $0.10 = $0.30 Result: Still failed	System recognizes Category 1 Cost: $0.00 (no retries) Result: Customer notified immediately
Lost/stolen card is declined	System retries 3 times Cost: 3 × $0.10 = $0.30 Result: Still failed	System recognizes Category 1 Cost: $0.00 (no retries) Result: Customer contacted for new card
Insufficient funds decline	System retries after customer adds funds Result: Transaction succeeds on retry	System recognizes Category 2 Allows intelligent retry Result: Transaction succeeds on retry

How to Use This Service

Category 1 Decline Reattempt Protection is automatically enabled on all transaction requests. When you receive a declined transaction response, check the declineCategory field:

{
  "status": "Declined",
  "responseCode": "14",
  "responseMessage": "Invalid card number",
  "declineCategory": "1",
  "declineCategoryDescription": "Do Not Retry - Permanent Decline",
  "transactionId": "123456789",
  // ... other fields
}
        

In Your Code:

if (response.Status == "Declined") {
    if (response.DeclineCategory == "1") {
        // Category 1: Do NOT retry this transaction
        // Contact customer to update payment method
        NotifyCustomerOfPermanentDecline(customer, response.ResponseMessage);
        UpdatePaymentMethodStatus(paymentMethod, "Invalid");
    } else if (response.DeclineCategory == "2") {
        // Category 2: Temporary issue - may retry later
        ScheduleRetryAttempt(transaction, retryInHours: 24);
    }
}
        

2. Duplicate Check

What is this service?

Duplicate Check protects your customers from being accidentally charged multiple times for the same purchase. This can happen when a customer double-clicks a "Pay Now" button, when a network error causes a page to reload and resubmit, or when your system experiences a temporary glitch that sends the same transaction request twice.

Getting charged twice for the same item is frustrating for customers and creates extra work for your support team to process refunds. Even worse, it damages customer trust and can lead to chargebacks. Duplicate Check automatically detects and prevents these duplicate transactions before they're processed.

How It Works

Duplicate Check analyzes each incoming transaction and compares it against recent transactions (typically within the last 5 minutes) using multiple data points:

If all criteria match, the second transaction is flagged as a duplicate and rejected before processing, preventing the double charge from ever occurring.

Response Information

When a duplicate transaction is detected, you receive a specific response indicating the duplication:

Field	Description	Example Value
status	Transaction status	"Declined"
responseCode	Specific code indicating duplicate	"19" (Duplicate Transaction)
responseMessage	Human-readable explanation	"Duplicate transaction detected"
isDuplicate	Boolean flag for easy checking	true
originalTransactionId	Transaction ID of the original (successful) transaction	"987654321"

Benefits

Common Scenarios Prevented

Scenario	What Happens	Result with Duplicate Check
Double-click on submit button	Browser sends two identical payment requests	First transaction processed, second blocked
Network timeout causes page reload	Customer resubmits thinking payment failed	System detects original succeeded, blocks retry
Mobile app sends duplicate API call	App glitch sends same payment request twice	Duplicate detected within milliseconds
Scheduled payment retries too quickly	Automated retry happens before timeout expires	Duplicate blocked if within detection window

Important: When Duplicates Are Allowed

Duplicate Check is smart enough to know when charges should go through, even if they look similar:

How to Use This Service

Duplicate Check is automatically enabled on all transaction sale requests. When you receive a duplicate detection response, handle it appropriately in your application:

{
  "status": "Declined",
  "responseCode": "19",
  "responseMessage": "Duplicate transaction detected",
  "isDuplicate": true,
  "originalTransactionId": "987654321",
  "transactionId": "123456790",
  // ... other fields
}
        

In Your Code:

if (response.Status == "Declined" && response.IsDuplicate == true) {
    // This is a duplicate of a successful transaction

    // Retrieve the original transaction for the customer
    var originalTransaction = GetTransaction(response.OriginalTransactionId);

    // Show customer a helpful message
    DisplayMessage(
        "This payment has already been processed successfully. " +
        $"Transaction ID: {response.OriginalTransactionId}. " +
        "You have not been charged twice. If you have questions, " +
        "please contact support with this transaction ID."
    );

    // Log for audit purposes
    LogDuplicateAttempt(response.TransactionId, response.OriginalTransactionId);

    // Don't retry - the original already succeeded
    return;
}
        

Best Practices

3. Available Refund

What is this service?

Available Refund is an intelligent tracking service that tells you exactly how much money can be refunded for any given transaction. This is especially valuable because refunds can be complex—a single original transaction might have multiple partial refunds over time, and you need to know how much refund capacity remains before attempting another refund.

Without this information, you might accidentally try to refund more than the available amount, resulting in an error and a frustrating experience for both your staff and your customer. Available Refund eliminates this guesswork by calculating and displaying the exact refundable amount in real-time.

How It Works

Available Refund automatically tracks the refund history of every transaction and calculates the remaining refundable amount. This calculation takes into account:

The Formula:

Available Refund = Original Transaction Amount - (Completed Refunds + Pending Refunds)
        

Response Information

The Available Refund amount is included in the transaction details whenever you retrieve a transaction:

Field	Description	Example Value
originalAmount	The original transaction amount charged	500.00
refundedAmount	Total amount already refunded (completed + pending)	250.00
availableRefundAmount	Amount that can still be refunded	250.00
refundCount	Number of refunds issued against this transaction	2
refundHistory	Array of all refund transactions with amounts and dates	[{refundId, amount, date, status}, ...]

Benefits

Example Scenarios

How to Use This Service

Available Refund is automatically calculated for every transaction. When you need to issue a refund, first check the available amount:

// Step 1: Get the transaction details
GET /v1/rest/merchants/{merchantId}/transactions/{transactionId}

Response:
{
  "transactionId": "123456789",
  "status": "Approved",
  "originalAmount": 500.00,
  "refundedAmount": 150.00,
  "availableRefundAmount": 350.00,
  "refundCount": 1,
  "refundHistory": [
    {
      "refundId": "REF-001",
      "amount": 150.00,
      "status": "Completed",
      "date": "2026-03-20T10:30:00Z"
    }
  ]
}
        

In Your Code:

// Check available refund before attempting refund
public async Task ProcessRefund(
    string transactionId,
    decimal requestedAmount)
{
    // Get transaction details
    var transaction = await GetTransactionAsync(transactionId);

    // Check if refund amount is available
    if (requestedAmount > transaction.AvailableRefundAmount) {
        return new RefundResult {
            Success = false,
            ErrorMessage = $"Refund amount ${requestedAmount} exceeds " +
                          $"available refund of ${transaction.AvailableRefundAmount}. " +
                          $"Original: ${transaction.OriginalAmount}, " +
                          $"Already Refunded: ${transaction.RefundedAmount}"
        };
    }

    // Available refund is sufficient, proceed with refund
    var refund = await InitiateRefundAsync(transactionId, requestedAmount);

    return new RefundResult {
        Success = true,
        RefundId = refund.RefundId,
        RefundedAmount = requestedAmount,
        RemainingAvailable = transaction.AvailableRefundAmount - requestedAmount
    };
}
        

Display in User Interface

Show Available Refund information clearly in your admin panels and customer service tools:

UI Element	Display Information
Transaction Details Page	Original Amount: $500.00 Total Refunded: $150.00 Available for Refund: $350.00
Refund Form	Enter refund amount: [ $_______ ] Maximum refund: $350.00
Refund History Section	Refunds (2): • REF-001: $100.00 on 2026-03-15 • REF-002: $50.00 on 2026-03-20 Total: $150.00

Best Practices