The project type determines which invoicing procedure should be applied. Only the two external project types, time-and-material and fixed-price projects, can be invoiced. Time-and-material projects and fixed-price projects are always attached to an invoice project.

• Fixed-price projects – The invoice amount is based on invoice payment plans Invoice payment plans. Invoicing is performed through an on-account setup, also referred to as a payment plan. Fixed-price projects can be invoiced per project or per invoice project. For more information, see Invoice fixed-price projects.

• Time-and-material projects – The invoice amount is based on transaction lines that are entered on projects. Transactions can be invoiced per project or per invoice project. For more information, see Invoice time and material.

Time-and-material projects and fixed-price projects can be attached to the invoice projects as follows:

• On-account invoicing – Time-and-material projects and fixed-price projects can be invoiced on account. Two different types of on-account setups are required for the two project types.

• Invoicing in the periodic section – Through the periodic functions, transactions can be invoiced across projects. The periodic functions provide an overview of transactions to be invoiced.

• By using credit notes in invoicing – A credit note can be created for both time-and-material projects and fixed-price projects.