Our HOA in California, 35 years old and in well maintained, goes through the same process every four years, and you are fortunate that your association is responsible enough to actually do it. Our fees went up from $185 when we first bought 18 years ago, to $365 currently. There was also a $2500 assessment for the purpose of "restoring the reserve account." However, having gone through that process, they have been stable at $365 for five years.
Three things contribute to the increase. Items wear out that are not included in the reserve funding, items for which funding is provided wear out sooner than expected and therefor are not yet fully funded when that happens*, and the cost of replacement/repair of capital items increases and that increase has to be allowed for.
*The funding in the reserve is graduated, built up ofver the lifespan of the item so that full funding for it occurs when it reaches its expected lifetime. If something is expected to last thirty years but fails after fifteen, then only half of its replacement cost has been set aside at that time.
Our irrigation system was not included, for instance, as the original accountant did not know that it would wear out after thirty years and need extensive replacement of valves and controllers to the tune of $100,000. So we had to spend that money, and then we had to add contributions to the reserve to create the $100,000 to be there 30 years from now when it happens again. The monthly fee had to be increased to cover the costs of repair, and it had to be increased to cover the cost of additional funding of the rserve.
When a condo is built the original HOA is the builder, since he owns all of the units. He is the one setting the monthly fees and he will naturally set them as low as he can to make the units more saleble. There are laws governing how the "reserve study" must be conducted, but there is flexibility within those laws, and it sounds like your association is correcting some "optimistic assumptions" made by the original association calculations. I would not make any assumptions that siimilar increases would become common, and it sounds like you have a responsible board which is taking the hard actions now in order to prevent even harder action later.
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