Shopify Plus Checkout Customization After Scripts: Rebuilding Discount, Shipping, and B2B Logic

Shopify blocked editing and publishing of new Scripts on April 15, 2026, and every Script stopped executing on June 30, 2026. Any Plus store that depended on Ruby Scripts for discounts, shipping rules, or B2B payment logic now has to rebuild that behavior elsewhere.

Shopify Plus checkout customization now uses three components, including Functions for business logic, checkout UI extensions for what buyers see, and public or custom apps that can provide these capabilities where needed. This article guides you through each lost Script type to its replacement and covers the trade-offs.

Which Shopify Functions or Extensions Replace Scripts?

Scripts ran in one Ruby runtime. Functions are separate APIs, one per checkout decision, so one old Script may become several pieces.

Table Image: Alt Text: Shopify Functions vs Extensions

Auditing Existing Scripts Before Migration

Any Shopify Plus checkout customization rebuild starts by checking the Shopify Scripts customizations report in your admin. It lists the customizations active before Scripts were discontinued, including payment methods, shipping options, and product discounts. Since the Scripts are no longer working, list each rule, such as customer type, items in the cart, delivery destination, and expected result, as a test case before rebuilding it.

Pay attention to what the report cannot tell you. It describes what each Script did in general terms, but not the edge cases such as mixed carts, partial discounts, and split shipments that Scripts quietly absorbed. Past orders are the best place to find those cases.

For an overview of other recent Shopify platform updates, read our guide to Shopify Summer 2026 Editions.

Rebuilding Discount Logic with Shopify Functions

Expect Stacking to Behave Differently

Effective Shopify Plus checkout customization requires understanding how discount rules behave after migrating from Scripts. Shopify's migration guide notes that line-item Scripts ran after Shopify's own discount logic, including Function discounts. Function discounts instead follow the combination rules set on each discount, so a rule that used to stack silently may now be blocked. Set combination behavior per discount and test it.

Build or Install

Public apps built on Functions cover common requirements such as tiered or volume discounts, on any plan. Build a custom Function for proprietary rules, and use Cart Transform to change how line items are structured.

Choose the discount type that matches the old Script. Shopify offers product, order, and shipping discounts. For instance, a free-shipping offer should use a shipping discount rather than a product discount. Picking the wrong discount can also affect how one discount works with other discounts.

Customizing Shipping and Payment Options

Delivery and payment Customization Functions are important to Shopify Plus checkout customization and work with the options Shopify already offers. This facilitates the opportunity to hide, rename, or reorder delivery and payment options, but creating new shipping rates or payment methods is restricted.

Shopify processes checkout operations, including cart changes, product discounts, delivery options, delivery discounts, payment methods, and validation, in a specific order. Payment rules can use the cart total after discounts are applied, but discount rules cannot depend on the selected payment method. Rules that have been integrated into one Script may need to be split across steps.

Delivery Customization input can include buyer identity, delivery groups, delivery addresses, and cost, which covers most conditions shipping Scripts relied on, such as destination or cart value. Where a Script is based on customer tags or a custom attribute, confirm that the same data reaches the Function's input query before you commit to the design.

Rebuilding B2B Checkout Rules

Custom code is required only when existing B2B configurations cannot meet your requirements for how to customize checkout on Shopify Plus. The native B2B checkout rules include:

• Company-specific payment options: For eligible B2B orders, Payment Customization controls available payment methods and supports payment-term customization where available.
• Minimum order value or quantity: Cart and Checkout Validation blocks non-compliant orders.
• Segment pricing beyond catalogs: A Discount Function applies logic catalogs cannot, such as contract quantity breaks.

These features help create a customizable checkout page that meets specific B2B payment, pricing, and order requirements. Function input queries can include buyer identity and, in several APIs, company data. Confirm the field for your API version.

Consider a wholesale buyer on payment terms who should not see card payment at checkout, and whose order should not proceed below a contract minimum. Payment Customization handles the first rule and Validation handles the second, while a UI extension can explain either to the buyer, and both don’t need a Discount Function.

Where Checkout UI Extensions Fit

Checkout UI extensions are the supported option when you need to modify a Shopify checkout page. They operate within predefined checkout targets and can display messages, collect additional information, and explain why an order does not meet certain requirements. However, changes to the overall layout are restricted. Shopify Plus supports these extensions on the Checkout, Thank You, and Order status pages. Other eligible plans support extensions on the Thank You and Order status pages, subject to Shopify's plan and extension-target requirements.

For a broader look at Shopify's checkout migration requirements and extension options, read our guide to Shopify Checkout Extensibility.

Checkout requirements are managed collectively by the checkout UI extensions and Validation Functions. In practice, if a business requires a minimum order value, the Validation Function prevents an order below this threshold, while the UI extension explains to buyers why. The rule must be enforced in the Function rather than relying only on the interface.

The B2B approach works the same way: a UI extension can collect a purchase order number at checkout, while a Validation Function verifies the requirements linked to the buyer’s account. An extension is implemented once Shopify’s current documents support the available targets.

Public App, Custom App or Network Access

• Public app: Supports common Shopify checkout requirements, but features depend on the settings provided.
• Custom app: Requires Shopify Plus and provides control over business rules, but the business is responsible for app lifecycle management.
• External data: Access to external data through Shopify Functions depends on the Function API and eligibility requirements. Other stores can pre-populate the required information in Shopify metafields.

Finalize the solution by considering the possible number and complexity of their checkout rules. A public app meets the requirements for a store with a few conventional rules, while a store with contract-specific pricing, multiple customer segments, or ERP integrations calls for a custom app. A designated person should oversee the maintenance.

Maintaining Your Shopify Plus Checkout Customization

Scripts were edited directly in the Shopify admin, and functions are managed through an app that follows a development workflow. These maintenance best practices help reduce long-term costs.

• Store rules: Rules such as discount thresholds, pricing tiers, and customer groups can be stored as data, allowing new deployments to update these values, since the app manages the settings.
• Review API versions: Function APIs at Shopify are updated over time, so regular monitoring is required. This ensures changes are identified before a version becomes outdated, thereby reducing the risk of compatibility issues and unexpected disruptions.
• Document each rule: Record what each rule does, why it exists, and which test cases verify its behavior to understand the logic when changes are required.