Civil Procedure Rules 7.7
Claimants may want to issue a claim form in a civil claim but not want to serve it for some time. This may be to allow time for mediation/negotiations or because more time is needed to get the case in order before service of Particulars of Claim. Issuing a claim form but wanting time to serve it tends to happen when the Claimant is at or is very close to the end of the relevant limitation period. What is key from a limitation perspective is when you issue the claim, not when you serve it. As such you can stop the limitation period running by issuing the claim form but buy yourself time to find an expert, draft the particulars, negotiate etc. Under CPR 7.5 you must serve the claim form on the Defendant within 4 months of the claim form being issued. However, CPR 7.5 is subject to CPR 7.7 which allows the Defendant to issue a notice demanding service of the claim form before the end of the 4 month period. The notice must give the Claimant a minimum of 14 days' notice - which is not long at all.
There is no obligation on the Claimant's part to advise the Defendant that the claim form has been issued, but the Claimant will struggle to hide this fact if the limitation period has passed and negotiations are ongoing.
Of practical concern is that under CPR 7.4 the Particulars of Claim, setting out the detail of the case and the legal claims, must be served within 14 days of service of the claim form. As such if a Defendant notifies a Claimant that it wants the claim form served within 14 days, the Claimant has a total of 28 days in which to serve the Particulars of Claim.
In short, no claimant should assume they have 4 months to get their house in order!