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

# Plan Variants

> Group related plans under one base plan and keep their differences small

Plan variants let you model multiple versions of the same offer without duplicating the full plan. The base plan holds the shared definition, and each variant stores only the differences: usually a price change, an added item, or a different usage allowance.

> **Example** <br />
> A Pro plan has the same core features for every customer, but is sold monthly, annually, and as a higher-volume package. Model these as variants of `pro` instead of three unrelated plans.

Variants are most useful for:

* Monthly vs annual billing intervals
* A/B testing plan packages
* Volume ladders that share most features but differ in included usage or overage price

## Setting up

<Tabs>
  <Tab title="CLI">
    Define variants from a base plan in `autumn.config.ts`:

    ```ts autumn.config.ts theme={null}
    import { feature, item, plan } from 'atmn';

    export const emails = feature({
      id: 'emails',
      name: 'Emails',
      type: 'metered',
      consumable: true,
    });

    export const pro = plan({
      id: 'pro',
      name: 'Pro',
      price: { amount: 20, interval: 'month' },
      items: [
        item({
          featureId: emails.id,
          included: 10000,
          price: {
            amount: 1,
            billingUnits: 1000,
            billingMethod: 'usage_based',
            interval: 'month',
          },
        }),
      ],
    });

    export const proAnnual = pro.variant({
      id: 'pro_annual',
      name: 'Pro Annual',
      customize: {
        price: { amount: 200, interval: 'year' },
      },
    });

    export const pro100k = pro.variant({
      id: 'pro_100k',
      name: 'Pro 100k',
      customize: {
        price: { amount: 35, interval: 'month' },
        removeItems: [{ featureId: emails.id, billingMethod: 'usage_based' }],
        addItems: [
          item({
            featureId: emails.id,
            included: 100000,
            price: {
              amount: 0.9,
              billingUnits: 1000,
              billingMethod: 'usage_based',
              interval: 'month',
            },
          }),
        ],
      },
    });
    ```

    Push changes with `atmn push`.
  </Tab>

  <Tab title="Dashboard">
    1. Create or open the base plan
    2. Create a variant from that plan
    3. Change only the fields that differ, such as price or specific feature items
    4. Save the variant
  </Tab>
</Tabs>

## How variants work

Each variant is still a plan you can attach by ID, such as `pro_annual` or `pro_100k`. The difference is that Autumn keeps it connected to the base plan.

Use variants when plans share most of their features. If a variant changes many unrelated parts of the plan, create a separate plan instead.