Tax Abatements

No it doesn't! The realtor is dead wrong. The condo obtained the primary 421-a approval, which is technically only for the construction period, up to 3 years, but is allowed to extend for up to 3 years even if construction is complete because the city is so slow at processing 421-a applications. If the exemption is set to expire in 2011, the final 421-a isn't approved yet. Either the city is still taking its sweet time, or the developer forgot to file. You need to find out which it is. Call HPD at (212) 863-8540. It's a nightmare, but it might work. If it doesn't, ask the developer to provide evidence that they filed for the final application in the form of a letter of receipt from HPD. Good luck.

If my building has a 10 year abatement, when does it start? from first closing? from last?

I believe it's not related to the closings, but rather to the tax year, so if it's in effect for current year 2010/2011 (abatement tax year is from july to july), you'll be paying the abated amount; if it only becomes in effect as of 2011/2012, you'll be paying full taxes for the year but will be reimbursed by the city for the difference if the builder filed for taxes to start in this year.