English time expressions using 'within'

Members must log on to verify their account within 7 days after receiving their new PIN." So, what's wrong with this commonly-used Hong Kong time expression? Today's blog post offers some insights into how the word 'within' works in English….

One area of English that regularly poses challenges to Hong Kong users is time expressions. English time expressions work very differently from Chinese ones; some describe time as though it is a series of fixed points, and others describe time as though it is a constantly flowing stream. It is important not to get these two ways of talking about time mixed up.

In today's blog post we will take a look at  one such time expression, one that I find frequently occurring in government writing in Hong Kong. You can see it in sentences like the following:

• You must submit your completed application form within two months after receiving the form in the post. 
• Members must log on to verify their account within 7 days after receiving their new PIN.

The expression is "within [a specified time period] after…". It is widely used in Hong Kong when writers want to limit the time available for doing something. In both of the sentences above, the writers want to tell readers that they only have a limited time to complete some action. 

However, in English it is incorrect to combine within and after in a time expression like this. This is because within must be linked with a fixed time point, usually with the preposition of,  e.g.

• Return the form within 7 days of [receiving it].
• Please reply within 3 months of [the date printed on the letter].
• You must repay the loan within 5 years of [ signing the agreement].

In our original sentence, 'after receiving the form' is not a fixed time point expression, because the word after refers to an unspecified and unfixed period of time that follows the receipt of the form, and NOT the moment of receipt itself. 

Our initial two sentences must therefore be rewritten like this:

• You must submit your completed application form within two months of receiving the form in the post. 
• Members must log on to verify their account within 7 days of receiving their new PIN.