> ## Documentation Index
> Fetch the complete documentation index at: https://developer.transactbridge.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Update Subscription

> Update an existing subscription by changing the plan, billing frequency, item values, or retry configuration.

The <a href="https://docs.transactbridge.com/#b7abc54b-bf8a-4569-8f65-46b613600d47"> Update Subscription API </a> allows a merchant to modify an existing subscription without creating a new one. Depending on the changes requested, the billing impact is determined by the merchant's business rules and subscription configuration.

The API can be used to upgrade or downgrade plans, modify subscription items, change billing frequency, or update invoice reattempt settings while preserving the existing subscription.

***

## Subscription Update Flow

```mermaid theme={null}
sequenceDiagram

participant Merchant
participant TB as Transact Bridge
participant Subscription

Merchant->>TB: Update Subscription API
TB->>Subscription: Validate subscription
Subscription-->>TB: Subscription found
TB->>Subscription: Apply requested changes
Subscription-->>TB: Subscription updated
TB-->>Merchant: Updated subscription details
```

***

## Common Use Cases

| Use Case                       | Description                                                                                                                                                                         |
| ------------------------------ | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| Plan Upgrade                   | Move a customer from a lower-tier plan to a higher-tier plan (for example, Basic to Premium).                                                                                       |
| Plan Downgrade                 | Move a customer to a lower-priced plan or reduce the subscription commitment.                                                                                                       |
| Update Item Values             | Modify the products, quantities, pricing, or other item-level details associated with the subscription.                                                                             |
| Change Billing Frequency       | Change the billing cycle, such as Monthly to Yearly or Yearly to Monthly.                                                                                                           |
| Update Reattempt Configuration | Modify the retry policy for failed recurring payment attempts.                                                                                                                      |
| Credit on Downgrade            | When moving from a yearly subscription to a monthly subscription, the remaining unused value can be credited to the customer's account according to the merchant's business policy. |

***

## Supported Updates

The Update Subscription API supports modifications such as:

* Subscription plan
* Subscription amount
* Product or item details
* Billing frequency
* Retry (reattempt) configuration
* Billing settings
* Subscription metadata
* Tax configuration (where applicable)

***

## Update Lifecycle

```mermaid theme={null}
flowchart TB

A[ACTIVE Subscription]
--> B[Update Subscription API]

B --> C[Validate Request]

C --> D[Apply Updates]

D --> E[Subscription Updated]

E --> F[Future Billing Uses Updated Configuration]
```

***

## Plan Upgrade Example

```text theme={null}
Basic Plan (₹499/month)
        │
        │ Update Subscription
        ▼
Premium Plan (₹999/month)
```

***

## Plan Downgrade Example

```text theme={null}
Premium Annual Plan
        │
        │ Update Subscription
        ▼
Basic Monthly Plan

Remaining annual balance
        │
        ▼
Merchant Credit Wallet (Optional)
```

***

## Billing Frequency Change

```text theme={null}
Monthly
   │
   ▼
Yearly

or

Yearly
   │
   ▼
Monthly
```

***

## Notes

* The subscription remains the same; only its configuration is updated.
* Future invoices are generated using the updated subscription configuration.
* Billing adjustments, prorations, or credits depend on the merchant's business rules.
* Downgrades may result in customer credits based on the remaining subscription value.
* Updating the billing frequency affects all future billing cycles.
* Changes to the retry configuration apply only to future payment failures.