Does "until [date]" mean "before that date"?

Solution 1:

My default reading of that would be that you can deliver the product at any time on the 18th of August, 2011 and still be considered to have met your deadline.

If the deadline were 23:59 August 17, it would have been stated as "(before August 18, 2011)".

I will also note, though, that most people will consider "the end of the business day" rather than "the end of the day" to be the cutoff time, so you might be considered late if you turn it in after 17:00, if that's when your client normally closes their offices.

Solution 2:

Until, which means up to, generally includes the specified moment.

The kidnappers have given us until October 11th to deliver the documents.

Solution 3:

"until" doesn't really work in that context at all. A parenthetical clause in that sort of sentence usually indicates a restatement of the previous phrase in different terms in order to provide clarity. So let's replace the phrase in that sentence:

You need to deliver this product until August 18, 2011 to meet your deadline and get paid.

That would mean that you need to continually deliver it for two days. There are types of products where this is possible — running water comes to mind — but I doubt that is true in your case.

Regardless, "until August 18" and "within two days" are mutually exclusive phrases. They cannot mean the same thing.

I'd ask for clarification.

Solution 4:

I don't think the example is a well worded condition; likely it was a typo/copy editing oversight.

Until--in the most literal sense--is a true condition that becomes false upon the occurrence of the target event. Using that definition, until Aug 18th would mean that your last possible moment to comply would be Aug 17th, 23:59:59.99.....