Since when do you read newspapers?

[sitifan]

1. Since when do you read newspapers?
2. Since when have you read newspapers?
What's the difference in meaning between the above two sentences?

[Raymott]

1. Since when do you read newspapers?
2. Since when have you read newspapers?
What's the difference in meaning between the above two sentences?

They mean the same thing. They express a facetious doubt about whether the person actually reads newspapers.
If the question is meant literally, it would be more common to say, "When did you start reading newspapers?"