> For the complete documentation index, see [llms.txt](https://support.caspen.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://support.caspen.com/using-caspen/billing/payments/apply-an-existing-payment-to-an-invoice.md). # Apply an existing payment to an invoice Learn how to use an existing unallocated payment to pay a client’s invoice. ## **Overview** If a client has made a payment that has not yet been used, you can apply it to an invoice once the invoice is **finalized**. *** ## **Apply an existing payment** To apply an existing unallocated payment: 1. Go to **Billing** → **Invoices** and open the invoice (Actions → View, or click the invoice number). 2. Click **Pay invoice** → **Existing payment.**

A list of the client's **unallocated payments** will appear. 3. Enter the amount you want to apply. 4. Click **Apply**.

The applied amount will appear under the **Payments** section of the invoice.

The invoice’s Payments section shows the applied payment and the allocation number.

The **Payments** section shows the payment and the allocation number. *** ## How allocations work When a payment is applied to an invoice: * The invoice displays the payment with an allocation number * Clicking the allocation number opens the **Allocation** screen * From the Allocation screen, click **Allocated from payment** number to open the original payment record The Allocation screen shows:

The Allocation screen displays the allocated amount, allocated from payment, and allocated to invoice.

* **Allocated amount** (how much was applied) * **Allocated from payment** (the payment the money came from) * **Allocated to invoice** (the invoice the money was applied to) In the payment record:

*The payment record shows the amount marked as **Allocated** and lists the invoices it was applied to.*

* The payment shows an **Allocated** amount * The **invoices** that received the payment are listed * The payment and invoice link to each other for easy tracking This is especially useful when: * One payment is split across multiple invoices * Reviewing which invoices were paid using a prepayment or bulk payment *** ## **How to unlink an allocation** Payment allocations can only be removed from the **Allocation** screen. To unlink an allocation: 1. Click the **allocation number** on the invoice. 2. On the Allocation screen, click **Delete**. The allocation will be removed, and the amount will return to **Unallocated** in the payment record.