All s/h receive the same percentage maintenance increase. Since different apartments have different amounts of shares, not everyone will pay the same dollar amount for their maintenance increase. So, if the Board votes a 5% increase, everyone's maintenance will increase by 5%.

The Board is elected to represent the s/h and run the co-op. This includes the right to raise maintenance if they think that's the right financial decision. The Board has strict ethical and fIduciary responsibilities that is supposed to keep them in check. If enough s/h disagree with the way the Board runs things, then other s/h have a right to voice their opinion about the way things are run. They also have the right to run for the Board and get involved in running the co-op.

You're right that real estate taxes have skyrocketed, but so has the price of everything in the past few years due to inflation. Everything costs more, including the prices charged by your plumber, electrician, contractor, etc. Co-ops are also navigating the climate change/carbon emission laws enacted by NYC. That may very well also increase expenses to the co-op.

It's possible that the co-op had some large expenses (roof, elevator) they incurred before you moved in, so they may still be paying those off.

It's important for all s/h, especially new s/h like yourself to look at the big financial picture and not just what's happened in the past year or two. I always felt that you need to look at a 10 year period to review the co-op's expenses and revenues to get a more complete picture of the co-op's financial situation.

As far as potential new buyers requesting to see the last 5 years of maintenance fees, it's important that they also see the last 5 years of financials - to give them a complete and accurate picture of the co-op's finances. There may have been boiler and heating upgrades that the co-op made. These might have cost lots of money now, but will pay off in the long run.

Remember that the Board is responsible for making short term and long term decisions on behalf of the s/h in the co-op. You can also ask Board members why they raised the maintenance fees? Communication is very important, so don't be afraid to ask the Board directly if you have any questions. It's always better to ask the Board than to listen to fellow s/h, who may not have all of the information that the Board has.

Good luck.