Yes you can. Check
here for important dates regarding change of preferences.
To clear up issues, here's a brief explanation of the process:
- You submit your UAC application (be aware there is a closing date for on-time applications, otherwise you are hit with a massive late fee).
- You can change your UAC preferences at any time now if you wish
- You receive your UAI on Thu 18 December 2008.
- You can still change your UAC preferences now up until Wed 7 January 2009. If you change your preferences after this date they won't be considered in the main round (this is when the majority of offers are made).
- Wed 21 January 2009: Main round offers are made. The cutoffs for entrance into courses in the main round is also released. If you are eligible for one of your preferences you will receive an offer for this course (you receive an offer for the highest preference you are eligible for, so this may be your first preference or your second or your nineth. If you were not eligible for any of your preferences then you will not receive an offer. Note: You can only receive one offer in a round.
- If you did not receive an offer than you can change your preferences from Wed 21 January – Tue 27 January 2009. Your new preferences will be considered in the Late Round. It is important to realise that institutions will make offers in the Late Round only if courses have vacancies after the Main Round. Also the cutoff for the Late Round may be different to the Main Round (for example it may increase or decrease). This depends on the number of places available after Main Round acceptances.
This means just because you were below the cutoff in the Main Round for a course you won't necessarily gain an offer in the late round as there may not be vacancies or the cutoff may have changed.
- There is also a final round but only a small number of offers are made during this round.
See
here for info on the Rounds and Offers.