# Add a transaction type to an existing processing code

When you need to add another transaction type to an existing processing code, you can either create a new transaction type and add it or you can add an existing transaction type. In addition, when adding a transaction type, you can also add reversals at the same time.

To add another transaction type to an existing processing code:

1. From the main menu, select **Configurations** > **Processing codes & transaction types**.\
   The **Processing codes & transaction types** screen displays with the **Processing codes** tab open by default.
2. Select the processing code to which you want to add a transaction type.
3. On the **Processing code details** screen, select **Add transaction type**.
4. On the **Select processing codes types** screen, select one or more processing code types to associate with the transaction type.
   * **Authorization processing code**—This code is used to authorize a transaction. It specifies the type of request, such as a purchase, cash advance, or balance inquiry, and directs the transaction to the correct network for approval.
   * **Reversal processing code**—This code is used to cancel or reverse a previously authorized transaction. It releases the funds and prevents the transaction from being completed.
   * **Partial reversal processing code**—This code is used to cancel or reverse only part of a previously authorized transaction. It releases a portion of the funds.
5. Select **Next**. The **Transaction type** tab displays. This is the first tab in the process. The other tabs displayed depend on which processing code or codes you selected. Possible tabs are **Reversal transaction type**, **Partial reversal transaction type**, **Transaction flow**, and **Review**.
6. On the **Transaction type** tab, select either **Create new** or **Select existing**.
   1. If you chose **Create new**:
      1. Enter a unique transaction type name and transaction type ID using 4–9 numbers, greater than 7000.
      2. In the **Select the financial type and impact** section:
         1. Select if the transaction type debits or credits funds.
         2. Select if transactions appear on statements.
         3. Select **Next**.
   2. If you chose **Select existing**:
      1. Choose the **Select** button next to the existing transaction type you want to add.
      2. Select **Next**.
7. On the **Reversal transaction type** tab (displayed only if you chose this type of processing code type), select either **Create new** or **Select existing**.
   1. If you chose **Create new**:
      1. Enter a unique Reversal transaction type name and define Reversal transaction type ID using 1–6 letters and numbers.
      2. Select **Next**.
   2. If you chose **Select existing**:
      1. Choose the **Select** button next to the existing Reversal transaction type you want to add.
      2. Select **Next**.
8. On the **Partial reversal transaction type** tab (displayed only if you chose this type of processing code type), select either **Create new** or **Select existing**.
   1. If you chose **Create new**:
      1. Enter a unique Partial reversal transaction type name and define Partial reversal transaction type ID using 1–6 letters and numbers.
      2. Select **Next**.
   2. If you chose **Select existing**:
      1. Choose the **Select** button next to the existing Partial reversal transaction type you want to add.
      2. Select **Next**.
9. On the Transaction flow tab, select a key to define how processing code and transaction type are linked.\
   Note: A transaction flow defines how a processing code maps to transaction types and creates debit and credit entries after authorization.
   1. Select a key. Key options are:
      * **Principal**—Principal is the original amount, excluding interest and fees.
      * **Installment**—An installment splits a purchase or outstanding balance into multiple scheduled payments over time, with fees and interest calculated upfront.
      * **Contract**—Contract is the total amount, including the principal amount, interest, and fees.
      * **Custom key**—A custom key is any value you define, like fees or taxes.
   2. Select **Next**.
10. On the **Review** tab, verify that everything is correct and select **Finish**.

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> If no transaction category is associated with the processing code, its status on the **Transaction type** tab will be **Missing PC**.

You can also create transactions types with the [Create program transaction type](https://developers.pismo.io/pismo-docs/reference/createprogramtransactiontype) endpoint.