Take a look at these sentences
I need to do this until September 30th.
They will send this until the end of the day.
Your tax return needs to be done until the end of March.
All these sentences communicate deadlines, but there is a level of ambiguity. Are we saying that something needs to be repeated or there is a flexibility between now and something needs to be achieved?
The answer to this depends on the context.
‘I need to do this until September 30th’ means that something will continue until for now but will or should finish September 30th.
The physiotherapist told me that I will need to do this exercise everyday until the end of next month. (repeated action or process which finishes on a deadline)
If something has to be completed or achieved by a certain date, we say ‘by‘.
This must be done by July 26th, there is a lot to do.
The option to purchase will be withdrawn by the end of this quarter.
It is also possible to use ‘until‘ when something to describe when something must be completed.
We have until September 30th to do this. (We need to do this by September 30th)
Clients have until August 15th to register an interest . (Clients need to register by August 15th)
Both forms are popular and can be used, so why do we need to know and use both?
As in any language, fluency occurs when a speaker is able to use and understand different ways of saying the same thing. It is also important to avoid using the same expressions repeated as this can suggest a lack of fluency.
____
What deadlines do you have?
What has to be done by when?
When do you have until to complete the least important things?
What tips would you give on meeting deadlines?
Have you missed any deadlines recently, what happened?