Casual contracts are typically issued to cover a short-term gap in resources, eg. to cover peaks in workload or seasonal demands, a specific short-term project, or to provide short-term cover for a vacancy.
A casual staffing contract is appropriate for one-off, short-duration work lasting no more than 12 weeks.
Casual staff would not normally be issued another contract of this type within a 12 month period but where this is exceptionally agreed, there must have been a gap of no less than six weeks between contracts. Casuals are paid on the last working day of every month via payroll, and payments are subject to PAYE tax and NI deductions if appropriate.
Note: PhD students are not able to work more than 20 hours per week whilst studying in accordance with University regulations.