You can scale a fee for any service using a Client Variable, in this example we will look at scaling the fee for Accounts based on the client's annual revenue. 

First we need to create the variable, to do this navigate to Services > Custom Fields. Click Add Custom Field and give the new field a name:

As we are going to add more than one option, from the Field Type dropdown select Multi Dropdown:

To add your first value click the Values dropdown, type your first option and click enter to add it to your list, it will show as blue when added:

To add subsequent values click the Values dropdown, type the next value and click enter again. Each value need to be added individually:

Then tick the option to use this field as a Billing Variable:

To apply this scale to a service to enable you to make value-based changes, navigate to Settings > Services, locate the service you want to add it to and click the Service's name. In this case we've selected the Accounts service.

Add a base fee for this service in the Service Fee field, using the custom fields, you can add a calculation to this fee which can add, subtract (this is how you would add discounts), divide, multiple and even charge per unit. This will allow you to charge an accurate fee for your services:

Tick the option to Scale Fees on Client Variable, then select your Variable from the dropdown:

Click Select Options and pick your first fee option, then enter a monetary value:

To add subsequent options click Add Value > Select Options and add a fee.

To add a variation to this service for another Client Type scroll down to the bottom of the page and click Add Service Variation, then just add the fees for this Client Type. 

To populate the Variable for a client navigate to Clients, locate the client and click on their name. Once the client file opens click the Client Variables tab then click Edit:

Then select the Value from the dropdown:

When you create the client's proposal and tick on the service that scales fees from the Variable you've added the fee will then be adjusted to include the scaled charge:

To find out how to create a proposal read our Proposals article.