I just built a new addition on my home, bigger than my existing home. I want to move the service panel from the old basement to the new basement, I would like to do this using the 4/0-4/0-4/0 aluminum service wire run in conduit, it is about 45 to 55 feet. What is the code on this? Also what is the code on location of the panel? I planned on mounting it in a storage closet in the new basement, I know it can not be in a clothing closet and needs like 36" x 36" clearence.

Since your aware that a panelboard cannot be installed in a clothes closet, and needs 36 inch deep clearance in front, and 30 (thirty) inch wide, what is your question?

Diesel, there is a lot missing from your post.

How are you "moving" it? Are you extending from a main disconnect?
Are you moving the whole service, meter and all?
Will the run be inside the house or out?

A storage closet is fine, IF the clearances can be met and maintained. Also, besides no clothes, you cannot store "easily ignitable" material in there.
You would be better off in a dedicated utility closet with minimal storage.

The meter is attatched on the old house and I plan on extending the service wire from the meter 45 to 55 feet to the new addition inside the old basement in conduit. Is this acceptable?

The issue is where is the Main Breaker. If it is at the meter, then you can extend the feeder, which should already be 4 wire.

If the Main is in the panel, the existing 3 wire feeder can be extended by mounting outside, then enter the building and end at the panel immediately inside.

The 3 wire feeder to the panel, which contains the Main Breaker, cannot run inside any distance to get to the panel. If the feeder must run inside the building any distance, check with your local inspector, as most will not allow more that 10 feet of cable, then a main Breaker will need to be added at the meter location, and the feeder to the panel will then need to be 4 wire.

See why details are so important?

Ok, so if I understand you correctly, I can run this wire inside if there is a main disconnect outside at the meter, which I bought a 200 amp disconnect to do this. It also has to be four wire from the disconnect to the 200 amp service panel which has another 200 amp main in it... is this correct. The wire from the meter to the existing service box is 3 wire 4/0-4/0-4/0. So I will need to install my main disconnect outside going from the meter box to the disconnect with four wire (or can it be 3 wire) and from the disconnect I can enter the house run conduit and then pull a 4 wire from the disconnect to the new panel. Is this correct? Sorry for lack of detail.

Did I get this correct and thanks for all the help.

At the disconnect you would install the ground rods. When you realize that, you have 3 wire from the meter to the disconnect and 4 wire to the panel.

Neutral and ground connect together at the disconnect, BUT they remain separate at the panel. i.e. remove the neutral to ground bonding screws.

Neutrals to Neutrals, Grounds to Grounds.

You may need to buy a ground bar kit for the panel.

Technicly you could use a main lug panel. The 200 A breaker in the panel is not a requirement in your case, also technicly it could even be higher like a 400 A breaker.

Thanks for all the help.