Varying a Sinking Fund Levy

What you are looking at is raising a special levy, which is different to the annual strata levies.  So you are not varying the annual strata fees, you are imposing a special levy that is additional to the annual levies.

To raise a special levy you need to hold an extraordinary general meeting for the owners to approve that special levy.  Note that you need to follow certain requirements to requisition the meeting, and the motion to approve the special levy should have all the information necessary for the owners to be informed about the circumstances that require it.

Note that you can also put a motion to raise a special levy at an AGM, it’s just that an EGM is a different meeting to the AGM.

I assume you have found that the maintenance cost for something is likely to be less than expected when your sinking fund plan was adopted.

[You do have a sinking fund plan, don’t you?]

Why not just stick with the agreed levies for this year? Then next year, in the light of the new information, the AGM can pass a resolution to amend the sinking fund plan. Part of that amended plan would be a revised schedule of anticipated levies for each of the remaining years of the plan.

The money from this year’s contribution would not be lost. It can just sit in an interest-bearing account and slightly lower levies will be required in each of the next several years. 

In the ACT, where I am, you can amend the sinking fund plan at any general meeting. I also can’t see anything that would prevent a general meeting from amending the budget resolutions, including reducing the remaining levy payments, between AGMs. If it is the same where you are, I think you could change your financial arrangements in the light of the changed situation. The general meeting would have to satisfy all the usual requirements for giving notice etc. If you need a particular class of resolution for your budget decisions  at the AGM (eg. a special resolution), you would need the same class of resolution to amend those resolutions at this later general meeting. [In the ACT we went from needing a special resolution to only ordinary a few years ago.]

Ditto. In the ACT, the EC can call a general meeting any time it likes (subject to proper notice etc). Alternatively a petition by at least 25% of owners specifying the matter to be decided can require the EC to call a meeting. 

Schedule 2 Sect 31 applies, and specifically Clauses 2 & 3 where it states:

(2) A general meeting of an owners corporation (in this clause referred to as an “extraordinary general meeting” ), which is not an annual general meeting, may be convened by the executive committee at any time.

(3) The secretary of an executive committee or, in the secretary’s absence, any member of the executive committee must convene an extraordinary general meeting as soon as practicable after receiving a requisition for such a meeting signed by one or more persons entitled to vote in respect of one or more lots, the unit entitlement or the sum of the unit entitlements of which is at least one-quarter of the aggregate unit entitlements.

Part 3 of the Act prescribes how budgets and resultant levy contributions are calculated and raised, and whilst Sect 75 refers to these matters being determined at each Annual General Meeting, that’s merely because they’re nominally annual deposits, and it’s permissible to recalculate those in the circumstances that you’ve described and to resolve to amend the amounts at an Extraordinary General Meeting.