---
updatedAt: 2026-10-01T09:50:54.000Z
agentTools:
  projectIndex: https://docs.acquired.com/llms.txt
---

# One-off Pay by Bank (SIP)

A one-off Pay by Bank payment is a Single Immediate Payment (SIP), a real-time bank transfer where the customer authorises a specific amount in a single interaction. SIPs are part of [Pay by Bank](https://docs.acquired.com/docs/pay-by-bank).

## How it works

1. **Create a payment session.** Your server submits a POST request to [Create a single immediate payment](https://docs.acquired.com/reference/create-single-immediate-payment), specifying the amount, currency, and a redirect URL for the customer to return to after authorisation.
2. **Redirect the customer.** The customer is directed to their bank, either via the Acquired Hosted Checkout or your own UI built using the API. They select their bank, authenticate, and approve the payment.
3. **Receive confirmation.** Once the customer approves the payment, funds are transferred immediately over Faster Payments. You receive a webhook notification confirming the outcome, and the customer is redirected back to your site.
4. **Funds settle.** The payment reaches `executed` once the bank has sent it, and `settled` once the funds land in your Acquired ledger. Acquired then batch settles to your external bank account each working day. If your account settles externally rather than into an Acquired ledger, the status stops at `executed` and no `settled` webhook is sent.

One-off payments are best suited for e-commerce checkouts, ad-hoc payments from a client portal, and any scenario where a customer is making a single transaction.

The customer authenticates for each payment. For the device-specific experience, see [Customer authentication](https://docs.acquired.com/docs/pay-by-bank#customer-authentication).

**Integration options:** One-off payments can be taken through any of the [integration paths](https://docs.acquired.com/docs/pay-by-bank#integration-paths), either via [Hosted Checkout](https://docs.acquired.com/docs/pay-by-bank-in-hosted-checkout) or with your own UI built on the [API](https://docs.acquired.com/reference/create-single-immediate-payment).

| Step                         | Who acts    | What happens                                                                                                                | Resulting status                                |
| :--------------------------- | :---------- | :-------------------------------------------------------------------------------------------------------------------------- | :---------------------------------------------- |
| 1. Create the payment        | Your server | Create a payment request with the amount, currency and `redirect_url`.                                                      | —                                               |
| 2. Select bank and authorise | Customer    | Redirected to their bank via Hosted Checkout or your own UI, and approves the payment. They have 10 minutes to complete it. | `cancelled`, `declined` or `expired` on failure |
| 3. Bank executes             | Bank        | Funds move over Faster Payments. You receive a `status_update` webhook and the customer returns to your site.               | `executed`                                      |
| 4. Funds settle              | Acquired    | Funds land in your Acquired settlement account. Not sent for external settlement.                                           | `settled`                                       |

***

## Statuses and webhooks

For the possible payment statuses and how a payment progresses, see [Statuses](https://docs.acquired.com/docs/pay-by-bank-statuses). For the webhooks you will receive, see [Webhook Notifications](https://docs.acquired.com/docs/webhook-notifications-3).