New York Instructions for Billing for Time and Expenses for more than One Client includes different types of billing methods such as Project Billing, Client Billing, and Consolidated Billing. Project Billing: This type of billing requires the billing of expenses and time for a specific project, such as a legal case, consulting project, or marketing campaign. The expenses and time should be itemized and charged to the client who engaged the services. Client Billing: This type of billing requires the billing of expenses and time to a specific client, such as a business or individual. The expenses and time should be itemized and charged to the client who engaged the services. Consolidated Billing: This type of billing requires the billing of expenses and time for multiple clients in one invoice. The expenses and time should be itemized and charged to each client who engaged the services. In order to ensure that accurate billing is done, all expenses and time should be carefully tracked and documented. Timesheets and expense reports should be kept up-to-date and submitted to the client, and all invoices should be clearly itemized and contain the appropriate information.