Under rules in the Charities and Trustee Investment (Scotland) Act 2005, OSCR has until 22 August next year to remove from the register any charity for which it does not hold current contact details.
The regulator has so far contacted nearly 22,000 of the 30,000 charities on the list it inherited from HM Revenue & Customs, but it is still trying to reach 6,000 more.
"For charities that have failed to respond to our attempts to establish contact, now is the time to act," said Marieke Dwarshuis, head of charities at OSCR.
Charities that are unilaterally removed from the register have three weeks to appeal, after which they have to reapply for charitable status.
OSCR will not be recovering charitable funds from deregistered charities during the exercise, but hasn't ruled out doing so at a later date.
The Charity Commission is not planning to follow Scotland's lead, despite a recent call from outgoing chair Geraldine Peacock for an 'amnesty' to rid the register of 15,000 dormant charities. The commission said work in this area was "ongoing".