Who pays for that?
Who does pay for that?
What is the difference between these two sentences? Are both grammatically correct?
Who pays for that?
Who does pay for that?
What is the difference between these two sentences? Are both grammatically correct?
The first is correct and the best way to say it.
A simple rule when using the interrogative pronouns with a verb in a question. If the question is about the subject of the verb, you don't include do, does or did:
Who pays for that?
Who let the dogs out?
In case the question is about the object, you do include them:
Who does Santos love?
Who did the teacher punish?
Note that those examples are in simple present and simple past only. Things might change in other tenses.
Update:
Also note that You might use the second sentence if you want to use the emphatic do. The emphatic do is simple used when you want to emphasize a verb. For instance:
- I don't think you like this song.
- Come on! I really do like it a lot.
There is also the example stangdon mention below in the comments.