See UW Policy 6: https://uwaterloo.ca/secretariat/policies-procedures-guidelines/policy-6
UW Policy 6 (https://uwaterloo.ca/secretariat/policies-procedures-guidelines/policy-6) tells us that:
6. VACATION CREDITS - GENERAL NOTES ... B. All Vacation Credits earned in a Vacation Credit Year must be used by June 30 of the Vacation Year following, and are not to be accumulated from year to year. In special cases, a maximum of two weeks Vacation Credit may be carried over from one Vacation Credit Year to the next Vacation Credit Year with the written approval of the appropriate manager. Such vacation carry-overs must be planned, approved and recorded in advance by the appropriate manager. In highly unusual circumstances, the business of the University may require extraordinary vacation carryforward. On these occasions, a staff member may request approval to carry forward more than ten days. Department heads who agree with such requests must obtain the approval of the Provost prior to May 1st.
I.e. management may approve up to 10 days carryforward, however it's to be considered a special case.
C. Vacation Credits should not be used prior to the beginning of the Vacation Credit Year. Exceptions will be considered on an individual basis and may be approved at the discretion of the manager. If an exception is allowed, the amount of vacation taken should not exceed the amount of Vacation Credit available at that point in time.
I.e. management may approve using some of the vacation credit that has been earned in the current Vacation Credit Year, however it's to be considered a special case.
We consider our implementation of the policy in the context of the purpose of vacations:
Vacations are pre-planned breaks from the workplace, mutually arranged between managers and staff members and meant to provide an opportunity for refreshment and rejuvenation.
...
The positive effects of a refreshed and rested staff member can reduce the possible tension and stress that can arise from extended periods of hard work with no break.
Telling someone that they have to plan their vacations to have exactly 0 days left by July 1st isn't always practical, and doesn't seem to solve a real problem. It arguably creates one (staff stress). So instead, our approach has been to be flexible, within reason. The guidelines we've been using are:
From: https://uwaterloo.ca/secretariat/policies-procedures-guidelines/policy-6 (as of May 2013):
APPENDIX A
Vacation Credits
3 weeks after 1 year of service
3 weeks after 2 years of service
3 weeks after 3 years of service
4 weeks after 4 years of service
4 weeks after 5 years of service
4 weeks after 6 years of service
4 weeks after 7 years of service
4 weeks after 8 years of service
4 weeks after 9 years of service
4 weeks + 1 day after 10 years of service
4 weeks + 1 day after 11 years of service
4 weeks + 2 days after 12 years of service
4 weeks + 2 days after 13 years of service
4 weeks + 3 days after 14 years of service
4 weeks + 3 days after 15 years of service
4 weeks + 4 days after 16 years of service
4 weeks + 4 days after 17 years of service
5 weeks after 18 years of service
5 weeks + 1 day after 19 years of service
5 weeks + 2 days after 22 years of service
5 weeks + 3 days after 25 years of service
5 weeks + 4 days after 27 years of service
6 weeks after 30 years of service