Rudan Business Holding v Tridan Trusted Advisors: when costs budget variations will and won't be allowed

The High Court's judgement in Rudan Business Holding SA v Tridan Trusted Advisors AG & Ors offers a detailed examination of the jurisdiction to vary approved costs budgets under CPR 3.15A, with particular focus on whether the parties had acted "promptly" and whether the developments relied upon were truly "significant".

The underlying litigation concerned an unfair prejudice petition under section 994 of the Companies Act 2006, in which the petitioner and first respondent each held 50% of the shares in Leo Services Holding Limited. The petition alleged, amongst other things, that the second respondent had falsified a loan agreement of approximately $1.35 billion, had wrongfully removed the petitioner's nominee directors from Leo Trust Switzerland AG, and had purportedly transferred shares in that company and its Cyprus counterpart to entities wholly owned by him. The dispute was complex and multinational, involving Swiss court proceedings and Letters of Request under the Hague Convention.

Both parties applied to vary their costs budgets, which had been approved in early 2022. By the time of the hearing before Deputy ICC Judge Kyriakides, the petitioner was seeking total budgeted costs of approximately £4.84 million and the respondents approximately £3.4 million, representing proposed increases of roughly £2.27 million and £1.64 million respectively.

Applying Persimmon Homes Ltd v Osbourne Clark LLP [2021] EWHC 841 and Sharp v Blanks [2017] EWHC 3390 (Ch), the judge confirmed the two threshold requirements under CPR 3.15A: first, that a significant development has occurred since the last approved budget; and second, that the revised budget has been submitted promptly.

On significance, the judge found that the amended points of defence — which expanded the respondents' case from 21 to 51 pages and introduced entirely new allegations — constituted a significant development, as did the dramatic expansion of the disclosure exercise and the increased trial length (from eight to sixteen days). The Further CCMC listed for May 2025 similarly qualified, given that it could not have been anticipated when the original budgets were approved. However, increases arising solely from a change of solicitors and the consequent redistribution of work were not significant developments, nor were increases attributable solely to rising solicitors' hourly rates.

The promptness analysis proved fatal to the majority of the claims. Both parties had known of the additional pleading issues since mid-2022 and had effectively completed the disclosure exercise by January 2023. Despite this, neither filed revised costs budgets until April 2025 — a delay of nearly three years. The judge rejected the argument that it was proportionate to await the Further CCMC before filing a single consolidated revision. The purpose of costs budgeting is prospective control, not retrospective approval of incurred costs, and collapsing multiple significant developments into a single belated application defeats that purpose entirely.

The respondents' January 2023 budget fared no better: it had never been formally filed with the court and was therefore incapable of satisfying the submission requirement under CPR 3.15A(4).

The upshot is that budget variations were permitted only for the Further CCMC costs, trial preparation, and trial — the three phases where promptness was satisfied. All other proposed increases, including those for statements of case, disclosure, and witness statements, were disallowed on the promptness ground alone, leaving the parties to argue those costs before a costs judge at detailed assessment.

The judgement serves as a firm reminder that the costs budgeting regime demands ongoing vigilance. Where a development is significant enough to affect recoverable costs, the obligation to revise is mandatory and immediate — not something to be deferred for administrative convenience.

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