The Civil Procedure Rules 1998

Defendant’s counterclaim against the claimant

20.4—(1) A defendant may make a counterclaim against a claimant by filing particulars of the counterclaim.

(2) A defendant may make a counterclaim against a claimant—

(a) without the court’s permission if he files it with his defence; or

(b) at any other time with the court’s permission.

(Part 15 makes provision for a defence to a claim and applies to a defence to a counterclaim by virtue of rule 20.3)

(3) Part 10 (acknowledgment of service) does not apply to a claimant who wishes to defend a counterclaim.