Meaning of "by" when used with dates - inclusive or exclusive [duplicate]

If, in a contract fr example, the text reads: "X has to finish the work by MM-DD-YYYY", does the "by" include the date or exclude it?

In other words, will the work delivered on the specified date violate the contract?

As others have specified, the word by is generally synonymous with no later than when referring to a date or time.

However, it is important to note (and this is why I am adding another answer) that if all you know is "The work must be completed by MM-DD-YYYY", then the exact due date is still ambiguous.

Without additional information, 'due by MM-DD-YYYY' has a fair chance of meaning:

• Due at or before 11:59:59 PM on that date - that is, before the specified day ends.
• Due at or before 11:59:59 PM on the previous date - that is, before the specified day begins.
• Due at or before a specific time on the date, such as the end of the workday for the person receiving the work.

(the below veers off the topic of the word's usage, but I thought it was worth adding)

Because of this ambiguity, it is extremely prudent to seek more clarification

• At what time on that date does the deadline occur?
• Is it problematic to be too early?