Purpose – To allow onsite and offsite contractors to submit their hours on a weekly basis for approval by the client and collation / payment by the business.
Take a look at www.timesheets.com.au While I don’t require all of the functionality it has, it will give you a guide as to what I am trying to achieve.
I wish to host this through my existing serve which I believe is php based.

3 Interfaces required

Business / Admin Interface
Contractor Interface
Client Interface

Basic functionality for each interface:

Contractor Interface
The need to be able to enter the hours worked (ideally start and finish less breaks calculated) Mon – Sun for each client. They should have only access to their own clients.
The Contractor may have multiple clients. Contractor should be able to record notes that are only visible to them and the Administrator – not the client.
When complete the Contractor should be able to send to Client for approval. Client to receive an email with a link(log in or log in directly via the link) and a means of approving the hours. Where the Contract has OffSite clients, this should be sent to Admin not the client.

Client Interface
Client should be able to approve each day – happy to have some form of electronic signature included. Client should be able to select not approved and have a notes field to provide information – say 1000 charachers

Business / Admin Interface
Set up clients and contractors with basic datas – name , contact, email phone etc.
Match the clients to contractors – select onsite and offsite
Run reports on who has and has not submitted timesheets
Reports on hours worked for all, some or one contractor over a chosen period.
Check box to send reminders to clients to approve hours
Check box to send reminders to contractors to submit hours (and to chase approval)
Mark off paid contractors when paid
Maybe – generate and track client invoices