Don't always have to

is usually preferred to / haven't always got to be

Lack of necessity, etc.: present/future

11.56.1 Lack of necessity: 'needn't', 'don't have to', 'haven't got to'

Reference to present or future time can be made as follows These forms are normally interchangeable [compare > 11.57.1]

Lack of necessity madvisability prohibition

be at the office (until 9 tomorrow)

I needn't leave until 9 (tomorrow)

don't have to be leaving untill 9 (tomorrow)

(Haven't got to is not generally used with progressive forms)

Won t (and shan t in BrE [> 9.36n3]) will combine with have to and

need to (full verb) for explicit reference to the future

/ won't need to/have to be at the office before 9 tomorrow

Inadvisability/prohibition: 'shouldn't/oughtn't to/mustn't', etc.

You shouldn't/oughtn't to/can't/mustn't be late for meetings

('present/habitual')

You shouldn't/oughtn't to/had better not/can't/mustn't be late

tomorrow (future)

Shouldn t oughtn t to had better not can t and mustn't are used to refer to the future, although they do not have future forms Possible alternatives are Shouldn t/oughtn t to/had better not can be replaced by

It won't be advisable (for her) to play games for the next month Can t and mustn t can be replaced by

We won't be allowed to park here for long

You will be forbidden to enter the courtroom before 9 30

Traffic in this street will be prohibited by law

Lack of necessity/inadvisability/prohibition: perfect/past

11.57.1 Lack of necessity: 'needn't have', 'didn't have to', 'didn't
need to'

Thes e forms mean roughly the same thing in e g / needn't have gone to the office yesterday I didn't have to (or/ didn't need to)go to the office yesterday (have and need are stressed) (= I went there, but it was unnecessary)

When have and need are unstressed, they mean something different from needn't have

I didn't have toll didn't need to go to the office yesterday

(= I knew it was unnecessary and I didn't go)

Because modals are defective [> 11.4 11.6.1] appropriate alternatives must be used in some tenses

It wouldn't have been necessary to change at Leeds if we had

caught the earlier train

I haven't had to cancel my appointment after all

If he had asked me I would have had to tell him the truth

11.57.2 Inadvisability: 'shouldn't have' and 'oughtn't to have'

Both these forms suggest criticism of an action
You shouldn't have paid the plumber in advance

Oughtn't to have

or failure to observe a prohibition

You shouldn't have stopped on the motorway

Oughtn't to have

11 Modal auxiliaries and related verbs

Uses of modals to express habit