We initially set up our contract templates to include (on top of all the basic, requisite information you may need) Billable rates, Job allowances, Assets and more.
The invoicing feature allows you to also decide whether or not you would like to include invoices on specific contracts for your customers.
You are able to customise these invoices according to the length of time of the contract as well as the price (obviously), and even included a setting that will automatically send off the invoice after it's been created (the checkbox above).
You can break these invoices down to decide whether or not you'd like to have a flat fee for all of your customers or whether you'd like to be able to make amendments on a customer-to-customer basis too. You can establish your VAT rate as well as any mark-ups too.
In the GIF above, you can see the various options available to set up your invoice as well as the ability to edit the markup once the invoice settings have already been filled in.
Please note -- you will not be able to use the payment portal link with your contract email invoices. If it is used (as a tag) in any of your templated invoice messages that go out associated with a contract, the link will not work.