Do you need です before から at the end of sentence?

[code]

    バスに乗りましょう。タクシーは高いですから。 
    
[/code]

or can you simply say `タクシーは高いから` without the `です`?




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.




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.

