By Tammy Hoang, QuickBooks ProAdvisor — Construction Bookkeeping Specialist Most HVAC maintenance plan programs are sold on instinct. A contractor picks a round number — $199, $250, $350 — because a competitor down the street charges something close, then hopes the math works out by year-end. It usually doesn't, and the books rarely tell a clear story. The problem isn't the idea of recurring revenue. The problem is that the HVAC maintenance agreement was never costed, and the