Difference between "does" and "has had"

Question

1. Since when does he not have a pen?

2. Since when has he not had a pen?

What is the difference between them?

Answer 1

Short answer:

Sentence 1. shows surprise and possibly anger, annoyance or doubt about him not having a pen.

Sentence 2. is ambiguous. It could mean exactly the same as sentence 1., or it could be a question about when he stopped having a pen.

Longer explanation

Let's start with the two meanings of "since when".

First meaning:
The two words can be used to ask about when something started:

Since when have the Winter Olympics been held? (since 1924)
Since when have you been unemployed? (since March 2020)

Second meaning
Merriam-Webster describes it like this:

since when idiom
--used to show that one is surprised and often angry, annoyed, or doubtful about what someone has said or done

"I'm a vegetarian." "Since when?"
"You told me to do it." "Since when did you start listening to me?"
Since when is it okay to cheat?

Note that this second meaning looks and sounds like a question, but is used rhetorically, and is not a request for an answer. Answering the question shows you don't understand the idiom, or you're purposefully ignoring the intended meaning. This second meaning is also somewhat rude and argumentative.

When using the first meaning --simply asking about when something started-- we must use a perfect tense with it, as in my two examples.

And if we want to use the second meaning --showing surprise and anger, annoyance or doubt-- then we often don't use a perfect tense, as in the Merriam-Webster examples. But it is possible to have the second meaning with a perfect tense:

Since when has anyone cared about what you had for breakfast?

Answer 2

Since when does he not have a pen? Let's make that declarative:

He doesn't have a pen since yesterday.

That is not standard English. It is colloquial. Think of this: He doesn't play tennis since yesterday.
In this case, you can see it is not standard. The present simple is for repeated action or a general statement. Not for when something started in the past.

The present perfect is standard English here:
Since when has he not had a pen? He hasn't had a pen [from the past until now, the time of speaking] since last week. [or more frequently: hasn't he had] Or: Since when?

• Since yesterday.

Without intonation from a voice, attitude cannot be determined. That said, they mean exactly the same thing but the simple present form would not be acceptable on an English exam.

Also, contracted forms are more frequent in spoken English and the standard English usage with since is the present perfect.

There is a sarcastic use of since when, yes. But your examples don't make it possible to declare that one is sarcastic and the other isn't.

Answer 3

Whilst they both mean the same when taken literally they have different meanings when used idiomatically in BrE.

"Since when does he not have a pen?" Is often used as an expression of annoyance, "he" is expected to carry or have been issued with a pen and have it available for use. It's similar to asking "Why doesn't he have a pen?"

"Since when has he not had a pen?" can be used in a similar way, but it can also mean "For how long has he not had a pen? [What happened to it?]"

Answer 4

They both mean the same thing. However, expect to hear "Since when does he not have a pen" more often.