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Incremental Authorization raises the hold amount on an existing pre-authorization without closing the transaction. Use it when the final charge is expected to exceed the original authorized amount, for example, an EV charging session that runs longer than the initial estimate.

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How It Works

An Incremental Auth sends a new authorization request against an existing transaction. The amount field represents the new total authorized amount, not the additional delta. If you authorized $50 and want to hold $75, send 75.00. The request links to the original transaction using two fields from the original Auth response: transactionId and transactionTimeUtc. Both are required. The processor uses them to locate and update the existing hold. After this call, the processor holds $75.00 against the cardholder. The original $50.00 hold is replaced, not stacked. The flow looks like this:

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Request

Send the following request body to POST /close-transaction to submit an Incremental Auth: 
{
  "basicInfo": {
    "requestType": 6,
    "entryMode": 1,
    "amount": 75.00,
    "currency": "USD",
    "countryCode": "US",
    "merchantRequestId": "INCR_AUTH_REQ_001",
    "transactionId": "ORIGINAL_NAYAX_TRX_12345",
    "transactionTimeUtc": "2026-03-18T15:00:00Z"
  },
  "machineInfo": {
    "machineId": "1001578171"
  },
  "cardHolderInfo": {},
  "paymentInfo": {},
  "additionalInfo": {},
  "validationKey": "<your-validation-key>"
}

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Parameters

The table below describes each required field in the request body:
ParameterTypeDescriptionRequired
requestTypeInt32Must be 6 for Incremental AuthRequired
amountDecimalNew total authorized amount, not the deltaRequired
transactionIdStringNayax transaction ID from the original Auth responseRequired
transactionTimeUtcDateTimeUTC timestamp from the original Auth responseRequired
merchantRequestIdStringA new unique ID for this incremental auth requestRequired
validationKeyStringHMAC key for request authenticationRequired

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Response

A successful validation returns a 200 OK status and a body containing the validated merchant details: 
{
  "status": {
    "verdict": "Approved",
    "code": 0,
    "statusMessage": "Payment processed successfully."
  },
  "basicInfo": {
    "amount": 25.5,
    "currency": "EUR",
    "merchantRequestId": "MERCHANT_MIT_001",
    "transactionId": "NAYAXTRANS98765",
    "transactionTimeUtc": "2025-08-28T10:30:00Z"
  },
  "paymentInfo": {
    "amount": 25.5,
    "currency": "EUR",
    "nayaxTokenId": "NAYAXTOK12345",
    "siteId": 1,
    "providerTransactionId": "PSP_TRANS_ABC",
    "decimalPlace": 2
  }
}

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Response Parameters

The table below describes the parameters of the response:
ParameterLocationTypeDescription
verdictstatusString’Approved’ or ‘Declined’. The final decision.
codestatusInt32Response code: 0 for Approved, otherwise the relevant decline code.
statusMessagestatusStringA descriptive message about the transaction outcome.
amountbasicInfoDecimalThe transaction amount processed.
currencybasicInfoStringThe currency of the transaction.
merchantRequestIdbasicInfoStringThe unique ID from the original request.
transactionIdbasicInfoStringThe unique transaction ID assigned by the Nayax system.
transactionTimeUtcbasicInfoDateTimeThe UTC timestamp when the transaction was completed.
nayaxTokenIdpaymentInfoStringThe token ID used for the charge.
siteIdpaymentInfoInt32The site ID associated with the payment.
providerTransactionIdpaymentInfoStringThe unique ID assigned by the Payment Service Provider (PSP).
decimalPlacepaymentInfoInt32The number of decimal places used for the currency/amount.
transactionId and transactionTimeUtc must come from the original Auth response, not the pre-auth or any intermediate request. Using the wrong values will cause the processor to reject the request.