The words in to, into, on to, and onto can be very confusing at first but this information should help you understand it better.
Into is a preposition and will be part of a prepositional phrase. The phrase it is a part of will modify the verb (or verb phrase) before the phrase.
1. When she ran into the the elevator, the alarm was sounding.
2. Put the money into the box.
3. The moth turned into a butterfly.
“In” is an adverb in the phrase in to. When using into where in to is intended, the sentence can be quite absurd.
1. She turned her ballot in to the voting table.
2. She turned her ballot into the voting table.
On to vs onto works the same way as into vs in to does, except there are several instances where either form is correct. It all depends on the intended meaning. A good rule to follow is if you can use “up” before “on”, use onto. Here are some examples:
1. The responsibility fell onto the father’s shoulders.
2. He threw the book onto the chair.
3. We drove onto the New Jersey turnpike.
4. We drove on to the New Jersey turnpike.
5. The waitress adds the tip onto the check.
6. Please pass this information on to your students.
7. It would make more sense to shift the cost onto the company.
8. It would make more sense to pass the cost on to the company.
Remember the 2 expressions are not the same. If you make sure you know what you are trying to say, you will likely choose the right phrase or word.