A $1 billion-a-year property tax break under investigation as part of the federal probe of Albany corruption is up for renewal later this year — and affordable-housing advocates are howling.

The advocates — who say big developers who get the break aren’t making good on their end of the bargain to build affordable housing — have scheduled a rally Thursday outside City Hall, just before a City Council hearing examining the 421-a program.

“This is a program that is beyond repair and beyond reform,” charged one advocate.