What is a Funding Source?
A funding source represents a specific stream of money in your organization. It is attached to a top-level OU and can be allocated down through your organization to be used on a project.
Based on that project's spend plan, costs incurred in that project will be associated back to that funding source, enabling the tracking of funds across your organization. Funding sources are created with a fixed amount as well as a start date and end date for when funds can be used.
Alternatively, you can use reserved instances to fund AWS accounts. Reserved instances are a way to purchase the use of AWS resources at a discounted rate. For more information, see AWS Reserved Instances.