We are laying tonge groove flooring and we are going to be a foot short of being perfectly lining up with the living room so would it be ok to cut that foot wide piece and have it connected to the living room or should cut that to go under the sink base

sounds like you started at a wall instead of the center. without knowing the direction the boards are running as well as the floorplan of the house, i would say hide it under the sink.

No haven't started laying new subfloor yet ripped up all old flooring now going to start laying new flooring the joists are 24 inches apart and running north to south

still need the floorplan but are you doing the entire house or just a room or two? and how are you planning to transition?

Just doing the kitchen and trying to have it same level as living which the kitchen connects to

i'm sorry. i'm going to have to let someone else chime in here. good luck.

I can’t picture “Foot short of lining up with the living room”. Sounds like you are missing a few square feet of the new flooring? And you’re trying to figure out where the gap goes?

cut that foot wide piece and have it connected to the living room or should cut that to go under the sink base

I can’t make sense of this. Partially because ‘cut’ makes it sound like you are working with large sheets of flooring, not t&g. But also because of course you’re not gonna waste flooring under a cabinet when you don’t have enough so I must be misunderstanding you.

Pro builder/carpenter here.
It's typical to see a nice flush finish threshold strip in matching wood between rooms.
It's also typical to see flooring barely cobbled together/held back under base cabinets. It's a pain when you remodel and want to keep the floors, but I understand why people do it in these situations.

How thick is your subfloor you are laying?

Do not use the 12” piece in front of the door ways.

I’m confused about whether there is a 12” piece or not. OP could definitely be clearer.

I took it as a 12”x12” square or there’s a 12” gap along a wall. With 24” joist on centers he will need a thick subfloor and will need to lay the Floor across the joist opposite of the floor joist. Otherwise the floor will bounce up and down when it is walked on.

Subfloor is 23/32 and I am saying I will be about a foot short of meeting with the living room but guessing I will have to cut to make that all fit correctly