Learn Hardcore Korean: jigeumeun hyeongeumbakke eobseoseo kadeu gyeoljereul mos haeyo, geurigo sigando chungbunhaji anhayo. - Right now I only have cash, so I can’t pay by card, and we also don’t have enough time.

The topic marker -은/는 on 지금은 adds a contrastive, time-specific nuance: as for now/at the moment. It implies that the situation might be different at other times. Without it (지금), the sentence is still fine but lacks that contrastive emphasis.

How does 밖에 work here? Does it always require a negative?

밖에 means only/nothing but and must be followed by a negative predicate. Common pairings: 없다, 안 V, 못 V, 모르다, etc.

Correct: 현금밖에 없어요 (I have nothing but cash).
Incorrect: 현금밖에 있어요 (outside the meaning here, this is ungrammatical).

What’s the difference between 밖에 and 만?

밖에 + negative: stronger limitation, often with a nuance of insufficiency or problem. Ex) 현금밖에 없어서…
만: neutral only; can go with positive or negative verbs. Ex) 현금만 있어서… (I only have cash…). Both are grammatical; 밖에 feels more restrictive.

Do I need another particle after 현금밖에? Can I say 현금밖에는?

현금밖에 normally stands alone; don’t add 이/가/을/를 after it.
현금밖에는 is also correct and adds extra contrast/emphasis via -는.
Don’t confuse this with the locative phrase 밖에 (outside + at), which is a different 밖 + 에.

What does -어서 in 없어서 express, and could I use 없기 때문에 instead?

-아서/어서 links cause and result: because/since. 없어서 카드 결제를 못 해요 = Because I have nothing but cash, I can’t pay by card. -기 때문에 is more formal/explicit: 없기 때문에…. In speech, -어서/어서 is most common; -으니까 is also possible with a slightly stronger speaker stance.

Why use 못 해요 instead of 할 수 없어요 or 안 해요?

못 해요: cannot (inability due to circumstances/ability). Fits well here because lacking a card/payment method prevents it.
할 수 없어요: cannot (more factual/possibility-based); also acceptable.
안 해요: don’t/won’t (volitional refusal/habit). Not appropriate if the issue is inability, not choice.

Is 카드 결제를 못 해요 natural? What about 카드 결제가 안 돼요 or 카드로 결제 못 해요?

All are natural, with nuance differences:

카드 결제를 못 해요: I can’t do a card payment (focus on the speaker’s inability).
카드로 결제 못 해요: same meaning, highlighting the method with -로.
카드 결제가 안 돼요: Card payment doesn’t work/isn’t available (focus on the system or store policy).
You can also say 카드로 결제할 수 없어요 or verb-compound 카드로 결제하지 못해요.

Why use both 그리고 and 도 in 그리고 시간도 충분하지 않아요? Isn’t that redundant?

No. 그리고 connects two clauses/sentences (and). 도 on 시간도 adds the meaning also/even regarding time. It emphasizes that, in addition to the payment issue, there’s also not enough time.

Why is it 시간도 충분하지 않아요 and not 충분히 없어요? How does 충분하다 work?

충분하다 is an adjective (to be sufficient), so you negate it: 충분하지 않다. 충분히 is an adverb and doesn’t pair naturally with 없다 in this context, so 충분히 없어요 is odd. Baseline form: 시간이 충분하지 않아요. Here, 도 replaces 이/가: 시간도 충분하지 않아요.

Could I say 시간도 부족해요 or 시간(이) 별로 없어요 instead?

Yes:

시간도 부족해요: I’m short on time (more idiomatic and concise).
시간이 별로 없어요: I don’t have much time. These are very natural alternatives.

Is the comma before 그리고 okay? How would natives punctuate this?

Korean typically uses a period before 그리고 when connecting full sentences:

… 못 해요. 그리고 시간도 충분하지 않아요. A comma isn’t wrong in casual writing, but a full stop is more standard. You could also drop 그리고 and simply write two sentences in sequence.

Should 못 해요 be written with a space or together (못해요)? What about 안 돼요?

For impossibility/inability, standard spacing is 못 해요 (adverb 못 + verb 하다).
못해요 (one word) typically means be poor at (e.g., 수영을 못해요 = be bad at swimming), though many people don’t distinguish in casual writing. In careful writing, keep the space for cannot.
안 돼요 must be spaced. 안돼요 is a common mistake.

Any pronunciation tips for this sentence?

밖에 is pronounced close to 바께 due to tensing.
못 해요 often sounds like 모태요 (ㅅ before ㅎ becomes a [t]-like sound).
지금은 sounds like 지그믄 in flow.
않아요 commonly sounds like 아나요 (the ㅎ is silent; ㄴ carries over).

Is 밖에 here the same as the 밖에 in sentences like 밖에 나가요?

No. In your sentence, 밖에 is the particle meaning only and requires a negative. In 밖에 나가요, 밖 + 에 means outside (location), and it can pair with any verb/positivity.

Where’s the subject pronoun? Can I add 저는?

Korean commonly drops obvious subjects. You can add 저는 for clarity:

저는 지금은 현금밖에 없어서… (grammatical but heavy with two topics)
More natural: 저는 지금 현금밖에 없어서… or just the original without 저는 if context is clear.

What politeness level is this? How would I make it more formal or casual?

This is -해요 style (polite informal).

More formal: … 못 합니다. … 충분하지 않습니다.
Casual: … 못 해. … 충분하지 않아.