Abstract: A memory apparatus and method of operation is provided. The apparatus includes a block of memory cells arranged in strings and connected to word lines overlying one another in a stack. The apparatus includes a control circuit configured to determine whether the memory cells of the block are all programmed. The control circuit determines a boundary word line splitting the word lines into first and second word line sets connected to the memory cells that are respectively programmed and not programmed in response to determining the memory cells of the block are not all programmed. The control circuit applies a delta adjusted read voltage being a default read pass voltage minus a delta voltage to a subset of the second word line set separated from the boundary word line in the stack by at least an offset number of the word lines while reading a first group of memory cells.