Is there a difference between these two expressions? Are they perfect synonyms?
"To date" implies that the current state is unchanged from the previous state, while "until now" implies that it has just changed. For instance:
To date, the Foos have never won a game.
Would mean the Foos have not won a game.
Until now, the Foos never won a game.
Would mean that they just won their first game.
Those expressions could have slightly different meanings especially when talking about finance.
Compare the statements
To date, the fund has grown 25% since the start of the year.
Until now, the fund has grown 25% (since the start of the year?).
To date does a good job of conveying the process of tracking the progress. However, until now seems to imply that the fund's growth rate has changed, thus our second statement implicitly requires further elaboration. Besides, until now and since the start of the year don't go well together.
When used adverbially before the whole sentence, they have not much difference in some cases. But "to date" can also be used as an adverbial phrase modifying a verb phrase when referring to the present day, while "until now" is not suitable. The Free Dictionary uses such an example:
How much have you accomplished to date? [correct]
*How much have you accomplished until now? [incorrect]
I know that this is an old question but looking for differences between to date and until now, I just found this in the Oxford Dictionary
to date PHRASE
‘their finest work to date’
And both are marked as synonyms there.
The accepted answer uses different verb tenses to prove the difference when it seems that both are interchangable.