What is the test for whether an offer was open for acceptance?

Whether the offer ought reasonably to have been accepted is determined not by reference to the eventual order made but rather “whether, at the time the offer was open for acceptance, it would have been reasonable for it to have been accepted”. Such reasonableness is “to be assessed by considering such factors as the timing of the offer, whether it had some relationship to the claim … whether it could be easily evaluated, and whether some rationale for the offer was provided” (Hartshorne v. Hartshorne, 2011 BCCA 29 at para. 27).