Into normally shows movement towards or inside something.
- She walked into the room.
- Put the money into the account.
- The car crashed into a wall.
In to occurs when in and to belong to separate parts of the sentence.
- She came in to see me.
- He handed in his application to the manager.
Easy guide
If you mean movement inside, use into.
If in belongs with one part of the sentence and to belongs with another, use in to.