Set up booking add-ons for Square Appointments
About booking add-ons
Booking add-ons let you offer optional extras that clients can select when they book a service online. Add-ons are built using modifiers — items like deep conditioning treatments, express facials, or extended massage time that complement your core services.
When a client books online, they see available add-ons listed with your service. Each add-on can include its own price and duration adjustment. The total appointment time and cost update automatically based on what the client selects.
You control which add-ons appear for each service and whether they're optional or required.
Before you begin
You need an Square Appointments enabled.
You must have online booking enabled for your business.
You need at least one service created in your service library.
Create an add-on
Add-ons are created as modifier sets in your item library. Each modifier set can contain one or more add-on options.
Sign in to Square Dashboard and go to Items & services (or Items & menus or Items & inventory) > Modifiers.
Select Create a modifier set.
Enter a name for the modifier set (e.g., "Hair Add-ons" or "Massage Extras").
Add individual modifiers within the set. For each modifier, enter a name, price, and duration.
Under sales channels, enable the modifier set for Online Booking.
Select Save.
The duration you assign to each modifier extends the total appointment time when a client selects that add-on.
Attach add-ons to a service
After you create a modifier set, connect it to the services where you want add-ons to appear.
Sign in to Square Dashboard and go to Items & services (or Items & menus or Items & inventory) > Services.
Select the service you want to edit.
Scroll to the Modifiers section and select Add modifier set.
Choose the modifier set you created for add-ons.
Set the modifier as Optional or Required for the service.
Select Save.
You can attach multiple modifier sets to a single service. Each set appears as a separate group of add-on options during booking.
Understand how clients see add-ons
When clients book a service with attached add-ons, they see the following experience:
The client selects a service on your online booking site.
Available add-ons appear with their names, prices, and duration adjustments.
The client selects one or more add-ons (or skips if they're optional).
The total price and appointment duration update in real time.
At checkout, the confirmation displays the service and all selected add-ons with a combined total.
If you mark an add-on as required, the client must select at least one option before they can continue booking.
Manage add-ons
You can update or remove add-ons at any time.
Edit an add-on: Go to Items & services > Modifiers, select the modifier set, and update the name, price, or duration.
Remove an add-on from a service: Open the service, scroll to Modifiers, and remove the modifier set.
Disable online visibility: Edit the modifier set and turn off the Online Booking sales channel. The modifier remains available for in-person use.
Change optional to required: Open the service, select the attached modifier set, and toggle between Optional and Required.
Changes take effect immediately on your online booking site.