Appropriate "No, I don't have" response to "お持ちでしょうか"

Question

I'm regularly asked at shops/supermarkets with something like:

ポイントカードはお持ちでしょうか　

My understanding is that the person is asking if I have a point card. I've also read What's the difference between でしょうか and ですか at the end of a question? that adding a でしょうか basically just means that person is guessing or wondering if I have a point card.

What is the appropriate way to say "No, I don't have one"?

I understand 持ち comes from もつ (to have).
But I'm not sure if I should say:

• 持たない (negative of もつ)
• もっていません (progressive, "not carrying one right now")
• simply ない (seems off because the question is not using ある）
• or some other?

I've tried all 3 and they seem to understand.
But maybe there's one that's most appropriate.

Answer 1

First, the でしょうか ending serves a softening function and demonstrates uncertainty, making the question sound less direct, akin to 'I wonder if you might have a point card?' rather than 'Do you have a point card?'.

The clerk is asking if you currently have your point card on your person and, indirectly, if you would like to use it. As this is a continuous/progressive state of possession, you would not use もつ or the negative equivalent もたない. Not owning a point card (encompassing past present and future - infinitive form) you would use もつ or もたない. Upon hearing this though, the clerk might think that you might want one.

Possible answers include: もっていません/もってません, もっていない/もってない（です）, ない（です）, or simply いいえ. You can also start with いいえ, then add one of the other responses (This would be my recommendation).
Some people might use けっこうです or だいじょうぶです, but that sounds like you're saying 'No thank you' (turning down an offer), which while understood to be a response in the negative still sounds wrong, as it is not actually answering what was asked.