If you want to sell additional services/products to your customer to enhance your sales revenue then Addons is the best option.

Addons can be added in a subscription while:

  • creating the Subscription
  • changing/updating the Subscription
  • In addition to this, for the non-recurring addons, with the help of Add Addon action on the Subscription or Customer details page.

Generating an Addon

Generate an addon by navigating Product Catalog > Addons > Create a New Addon and fill the given form.

Basic Addon Characteristics

Below given are some necessary characteristics of an addon:

Addon name

There must be a Name section for an addon. On the user interface of ChargeMonk, this name will be used to refer to the addon. It is necessary to have a name for addon here that should be eloquent of the characteristics of the addon like its period and pricing so that you can differentiate it easily from the other addons in your site.

So, in the place of naming addons as Addon A, Addon B, etc., it should be named as "SMS Credits monthly USD", "Custom Reports quarterly AUD" etc.

Invoice name

To delineate the name of an addon like it will be visible to the customer, an invoice name section is used. Invoice name is used for the addon in invoices, hosted checkout pages and the customer portal and quotes.
Therefore, the invoice name for an addon should be that which you want the customer to link with the addon.


The addon name is used at the place of invoice name in case you do not set the invoice name.

Addon description


This is given only on the change subscription screen.

The Addon description is a short description of an addon for the customer.


There are two types of addons: recurring or non recurring.

Recurring Addon

This type of addon renews as per the renewal of the subscription.

A Period
needs to be defined for recurring addons. This is that period which is covered for the price of an addon. A recurring addon is permitted only to get linked to a subscription that has a billing period which is a multiple of the period of an addon.

Therefore, assume that the below given statements hold:

  • Assume that an addon's period is 4 months, it cannot be linked to the subscriptions with billing periods that have an odd number of months.
  • Assume that an addon is of the period of 1 year, it can be linked to a subscription of the billing period of 24 months.
  • Addons having week-based periods can be linked only with subscriptions having week-based billing periods.
  • Addons having a day-based period can be linked only with subscriptions having the billing periods in the multiples of the addon period days. Such as,
    • An addon of 15 days can be linked only with plan subscriptions of 30 days (not 1 month, because the in all months number of days are not constant)or 60 days or 45 days billing period.
    • Link a subscription of 45 days plan with addons having 1, 3, 5, 9, 15, 45 days billing periods.
  • To link an addon with the billing period in days to a plan subscription of an annual or monthly billing period is not possible, because a month or year does not have a constant number of days. In the same way, to add a monthly addon to a plan subscription with 45 days billing period is not possible.

An addon's billing price would be the addon's price multiplied by the number of addon periods that will go into a single subscription period.

Consider the following:
Plan billing period: 1 year
Plan price: $500
Addon period: 3 months
Addon price: $30
When the addon is signed-up for with the plan, we have the invoice as:
Plan cost: $500/year
Addon cost: $120/year ($30x4)
Total: $620


As mentioned above, the addon period does not decide when it is billed. Also, addons will get billed with the subscription. The addon period is used only to calculate the addon's billing price when linked to a subscription.

Non Recurring addon

A one-time addon or non-recurring addon does not get renewed. Therefore, for a one-off purchase only it can be used as additional data with an internet subscription.

Get more info about non-recurring addons here.

Pricing Attributes


Select the currency on which the addon will get billed. In case you do not see the preferred currency, listed, in ChargeMonk you need to enable the currency. A plan with a different currency cannot be linked to an addon.

Note: In ChargeMonk, to define an addon, you only have one currency. In case you want to get multiple currencies for an addon then for each currency you have to create separate addons.

Pricing model

The below given options are available for an addon pricing:

  1. Flat Fee
  2. Per Unit

1. Flat Fee
Flat Fee is the type of addon used for services/ products that do not have a quantity linked to them. Therefore, for the addon period it has a fixed price.


For online storage in association with a subscription if you sell the "Premium Support", this will be a "Flat Fee" addon. And no quantity will be linked to it.

2. Per Unit
Price per unit addons will be used once products are charged in per unit of quantity.

You can sell anti-virus software (priced per device) as an addon.
The configuration would be:
Addon pricing: Per unit
Unit of measure: device
Price: $10
Charge type: Recurring
Period: 1 month
This addon would then be charged $10/device/month


In case tax profile have been setup, you can decide on exempting an addon from taxes by un-checking while generating an addon.

Tax Profile

If you want to keep the addon taxable, for it you have to select a tax profile This would be specified during the invoicing regarding what taxes are imposed on the price of the addon.

Addon Actions

You will see the actions panel placed on the right in the details page of any addon. The below given actions are available:

Edit Addon

This option allows you to change the configuration of addon.

You cannot change the Addon Id for an addon, once it has been generated.

In case there are no subscriptions linked to an addon, then every aspect can be changed without Addon Id.

In case subscriptions are linked to the addon, in that case everything can be amended except the below given factors:

  • Addon Id
  • Addon Charge Type (Recurring/Non recurring)
  • Addon Period
  • Pricing Model
  • Currency
  • Shipping preference (only if order(s) has(have) been created for the plan)

Addon Price Change

Once the subscription is attached to an addon, the addon's price can be changed(however, if the addon pricing is flat fee or per unit).

Navigate to Product Catalog > [Addon name] > Edit Addon. Add the new price of the addon in the Pricing field. Hit Update Addon.

The new price is imposed on all new subscriptions with the addon. Current subscriptions are not influenced and remain renewed with the old addon price.


Archiving/ Deleting an addon depends on if it has any subscriptions linked to it.


  • You can delete an addon when no subscriptions are connected to it. When deleted, the addon is eliminated from ChargeMonk completely and it does not show on the catalog of addons.
  • Whenever an is eliminate, you can reuse its name and Id.


Is it possible to add recurring addons to a subscription in the middle of its term?
Yes, it is possible and can be performed by choosing Change Subscription in the catalog of actions available on the details page of subscription. In case proration is activated, the addon's charge for the remaining term of the subscription is prorated. In case it is not activated, then the addon is charged from the next renewal.

Is it possible to control the number of times a recurring addon should renew with the subscription?
Yes, to do this, activate the billing cycle for addons.

Is it possible to have trial periods for addons too?

Yes, activate addon trials for this.

That product or service which is modeled into ChargeMonk and does not renew with the subscription even when it is connected to it is known as non-recurring addon. An ad-hoc charge which is against a customer and is not associated with any specific subscription is known as a one-time charge. To get more information about the above given two ways of charging visit here.

If I have a usage-based subscription system, in what way it should be handled that in ChargeMonk?
Use the metered billing feature of ChargeMonk to use the non-recurring addons to implement usage charges.

CIs it possible to see how a plan/addon looks like with tiered pricing in ChargeMonk's Self-serve Portal or Checkout?

Yes, check this FAQ.