I have attended a number of assessments recently where the Costs Judge has taken a very strict line when considering whether or not to allow a party to depart from its last approved costs budget, even where there is clearly good reason to do so. This is because there are mechanisms in place to allow that party to request permission to revise its budget during the claim rather than hoping for the best upon service, and thereafter assessment, of the bill of costs. Accordingly, the Costs Judge is bound by the costs management order and cannot depart from the approved budget.
The position, now, is that if you expect to depart from your last approved costs budget, you should first prepare a varied budget using Precedent T (CPR PD 47) and serve it on the other party and try to agree the changes. If the changes are agreed, the Court's approval should be sought thereafter. If the changes cannot be agreed, the Precedent T should be filed at court with a request for permission to revise the last approved costs budget. It is not clear from the Rule (CPR 3.15A) whether a formal Application is required, but it can't hurt, so my advice would be to lodge the Precedent T as an attachment to a formal application.
Leave this to chance at your peril. If you have done the work, you should get paid for it, but you won't if you do not comply with CPR 3.15A even if you are able to show "good reason" to exceed budgeted costs.
If you require any assistance in updating your last approved costs budgets, please contact us at firstname.lastname@example.org or by telephone on 01244 256865 and we will be happy to help.
Director, Costs Lawyer, Accredited Mediator