This is governed by the Davis-Stirling Common Interest Development Act (California Civil Code §§ 4000-6150). The answer depends on whether the assessment exceeds certain thresholds:
Under § 5605, the board can levy special assessments without a member vote, but only up to 5% of the association's budgeted gross expenses for the current fiscal year. If the assessment exceeds that 5% threshold, a vote of the membership is required, and it must be approved by a majority of a quorum of the members.
Let's do the math. If your HOA's annual budget is, say, $200,000, then 5% is $10,000. A $600,000 special assessment absolutely exceeds 5% of virtually any 40-unit HOA's annual budget. So yes, a member vote was almost certainly required.
There is an exception for emergencies under § 5610, but "emergency" is narrowly defined: it must involve an immediate threat to health and safety, or an extraordinary expense required by court order. A roof that needs replacement (not one that collapsed) typically doesn't qualify as an emergency.
Your options:
- Demand the board call a special meeting for a proper member vote under § 5605
- If 5% of the members petition for a special meeting, the board must hold one within 35 days (§ 4515)
- Challenge the assessment as void if it was levied without the required vote
- Request a review of the reserve study — the board is required to conduct one every three years (§ 5550)