The High Court has this week delivered a firm reminder that costs budgeting is meant to be a prospective exercise, not a running total that can be revisited whenever a case takes an unexpected turn. In Bassey v Whittaker & Watford Insurance Company Europe Limited ([2026] EWHC 2126 (KB)), Mr Justice Cavanagh allowed an appeal against a district judge’s decision to permit a variation of the parties’ costs budgets, confirming that the court has no general, freestanding discretion to vary a costs budget where there has been no “significant development” in the litigation.  

For costs lawyers and costs draftsmen, this decision is worth reading closely, not because it announces a new legal test, but because of how strictly it was applied to a fact pattern that will feel entirely familiar from everyday personal injury practice. 

What the Court Was Asked to Decide 

The underlying claim was a personal injury matter in which the district judge had permitted a variation of the costs budgets originally approved by the court. The developments relied upon to justify that variation were, on their face, unremarkable: additional work by medical experts, a modest extension to the trial window, and further disclosure. On appeal, the central question for Cavanagh J was whether the court retains any wider power to vary a costs budget where the parties do not agree to a revision, in circumstances where the significant developments test set out in CPR 3.15A has not been met. 

His answer was unambiguous. There is no such wider discretion. Allowing one, he observed, would risk exactly the kind of “constant tinkering” with costs budgets that the overriding objective and the interests of justice are designed to guard against. 

Why the Developments Did Not Qualify 

What makes this decision genuinely useful for practitioners is not the restatement of the legal test itself, but the court’s application of it. CPR 3.15A requires a development that was not, and could not reasonably have been, anticipated by the applicant at the time the previously approved budget was drawn up. Cavanagh J found that none of the three developments relied upon met that standard. 

His reasoning on the medical evidence point is particularly instructive. He observed that in a personal injury case, the need for further expert reports and quantum statements is “almost always a possibility,” and that here, the prospect of the claimant’s condition changing as a result of new therapy or rehabilitation was an obvious one at the time of the original costs budgeting exercise, not least because it was already known that a move in accommodation was in prospect, which itself widened the range of therapy and rehabilitation that might become relevant.  

In other words, the very unpredictability that might once have been used to justify a variation was, on these facts, entirely foreseeable, and foreseeability is fatal to a significant developments argument. 

Consistent With the Direction of Travel 

This decision does not stand in isolation. It follows the same restrictive approach set out by Master Kaye in Persimmon Homes Ltd v Osborne Clarke, where a substantial application to increase an approved costs budget was dismissed after each of the claimed developments was found, on analysis, to have been reasonably foreseeable rather than genuinely unexpected.  

Read together, these decisions suggest the courts are continuing to apply CPR 3.15A narrowly, and are unwilling to treat routine, if inconvenient, developments in litigation as a basis for reopening an approved budget. 

What This Means in Practice 

For solicitors preparing a costs budget, the practical message from Bassey v Whittaker is to budget realistically at the outset for the kinds of developments that experience shows are common in that type of claim, rather than assuming a shortfall can be corrected later through a variation application. In personal injury litigation specifically, that means factoring in a reasonable prospect of further expert evidence and quantum updates from the start, rather than treating these as unforeseeable extras. Of course, the parties have access to contingency phases wherein, additional experts fees and time can be included and should the need for these arise, the contingency “triggers” thereby removing the need for further budgeting case management. 

For costs lawyers and costs draftsmen advising on budgets, this decision reinforces the value of scrutinising a draft Precedent H closely at the outset, and pressing for realistic contingency within each phase, since the door to a later variation is, in practice, narrower than some practitioners may have assumed. Where a genuine variation application is being considered, this decision is also a useful reminder to focus tightly on demonstrating true unforeseeability, rather than simply pointing to the fact that a development has increased costs. 

Speak to Greener Costs Today 

If you need support preparing a realistic costs budget from the outset, or advice on whether a proposed variation is likely to meet the significant developments test, contact Greener Costs’ costs lawyers and costs draftsmen on 01204 263047 or info@greenercosts.co.uk. 

FAQs 

Can a costs budget be varied by agreement between the parties? Yes. CPR 3.15A allows for variation where the parties agree, and the usual process for a significant development still requires the particulars of any revised budget to be submitted to the other party, and then the court, promptly. 

What counts as a “significant development” under CPR 3.15A? A development that was not, and could not reasonably have been, anticipated by the applicant at the time the previously approved budget was drawn up. Developments that were foreseeable at that stage, even if they were not certain to occur, are unlikely to qualify. 

Does this mean costs judges can never depart from a budget? Not entirely. At detailed assessment, a costs judge retains a separate power to depart from an approved budget where there is good reason to do so. Bassey v Whittaker concerns the court’s power to vary a budget during the litigation itself, which is a narrower and distinct question.