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```

    バスに乗りましょう。タクシーは高いですから。 
    
```

or can you simply say `タクシーは高いから` without the `です`?
CC BY-SA 3.0
2014-06-11T03:46:13.970
17361
2014-06-18T10:21:49.927
4910
question
grammar usage
Do you need です before から at the end of sentence?
Yes, it's grammatically correct. です is just a polite expression. I would
prefer to add です when I am in a formal situation or with senior people.
CC BY-SA 3.0
2014-06-11T03:55:46.913
17363
2014-06-11T03:55:46.913
6541
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answer
As Tomiyoshi notes, です is a polite marker, much like the -ます ending on verbs.
The plain form is だ, corresponding to the dictionary or plain form of verbs.
In technical terms, this です・だ word is often called a "copula" (after _-i_
adjectives, です is instead regarded as a politeness marker). Whether either
form is required at the end of a sentence depends on two things: 1) the
grammatical structure, and 2) the social register (i.e. the context, who
you're talking to).

### Grammar

Generally speaking, if a sentence ends in a noun or a _-na_ adjective, you
need to use the copula (either だ or です, depending on social register).

If a sentence ends in an _-i_ adjective, as in your sample sentence, adding だ
in informal contexts is actually considered incorrect grammar, since the _-i_
adjective is already grammatically complete on its own. In technical terms, an
_-i_ adjective forms a complete predicate (i.e. it works as a verb), so the
copula is not needed. However, _‑ i_ adjectives do not conjugate for
politeness (there is no -ます form), so in polite contexts, です is used as a
politeness marker, as a kind of replacement for -ます.

### Social register

If you're among friends, だ after nouns or _-na_ adjectives might be
appropriate as the less-formal plain form. If you're among strangers,
colleagues, or in a professional setting, you should use です, also after _‑ i_
adjectives.
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2014-06-11T05:54:59.587
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2014-06-12T19:04:48.170
2014-06-12T19:04:48.170
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answer
> Do you need です before から at the end of sentence?

Not necessarily. It depends on how polite you want to be.

> バスに乗りましょう。タクシーは高いですから。  
>  or can you simply say タクシーは高いから without the です?

Yes, both are correct. You can say:

> バスに乗りましょう。タクシーは高いですから。(polite form)  
>  バスに乗ろう。タクシーは高いから。(casual form)

because these are inverted sentences of:

> タクシーは高いですから、バスに乗りましょう。(polite form)  
>  タクシーは高いから、バスに乗ろう。(casual form)  
>  (タクシーは高いから、バスに乗りましょう。is also fine.)

* * *

(You don't say *バスに乗りましょう。タクシーは高いからです。/*バスに乗ろう。タクシーは高いからだ。 because you don't
say *タクシーは高いからです、バスに乗りましょう。/*タクシーは高いからだ、バスに乗ろう。You'd use
タクシーは高いからだ。/タクシーは高いからです。 when you say "It is because taxi is expensive", as a
response to "Why do you take a bus?" etc.)
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2014-06-18T09:55:33.827
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answer