anchor.diff:  [start=3]
   . In the *New plan* field, select a different plan.
   . If you need to override the price for the plan you've selected, enter the amount in the *Price Override* field.
  -. To accept the default policy for when this change takes effect, leave *Default policy* selected and click *Save.*
  +. To accept the system's default policy for changing subscriptions (`END_OF_TERM`), leave *Default policy* selected and click *Save.*
   
   OR
   
  -Use one of the other two options – *Specify Policy* or *Specify a date* – to alter when this change takes effect:
  +You can select one of two other options: *Specify Policy* or *Specify a date*. This will override the policy defined in the catalog for the plan. (For information on this topic, see see https://docs.killbill.io/latest/userguide_subscription.html#_plan_change_timing["Plan Change Timing"] in the _Subscription Guide_.)
   
   * *Specify Policy*: You can select either `IMMEDIATE` or `END_OF_TERM`. For information on these two policies, see the https://docs.killbill.io/latest/userguide_subscription.html#\_subscription_alignment_rules["Subscription Alignment Rules"] section of the \_Subscription Guide_.
   
  
positive.code: This section explains how to add an add-on product to a customer's subscription.
  
  [NOTE]
  *Note:* To add an add-on to a subscription, the add-on must exist in the catalog. For information on adding an add-on to the catalog, see <<part_6_tenants_and_admin>>.
  
  1. Open the account and click *Subscriptions* on the sub-menu.
  2. Hover over the gift icon and click *Add add-on*:
  
negative.code: |===
  
  ==== Update the Billing Cycle Day
  
  The https://docs.killbill.io/latest/userguide_subscription.html#_billing_alignment_rules["Billing Alignment Rules"] specify whether billing occurs at the account/subscription level or bundle level.
  
  [NOTE]
  *Note:* If you update a subscription BCD in Kaui, this BCD overrides what is specified in the billing alignment rules in the catalog.
  
  Follow the steps below to update the billing cycle day (BCD) defined for a subscription. These steps assume the subscription is billed on a monthly basis.
  
  