“Appropriate & Necessary”:
A Tailored-Disclosure Standard for Maintenance Variation Applications
(Commentary on D.D v N.B.T. [2025] IEHC 402)

1. Introduction

D.D v N.B.T. is a High Court (Family Law) decision delivered ex tempore by Jackson J. on 11 July 2025. The respondent father (“N.B.T.”), a high-net-worth individual, applied to vary a 2021 Terms of Settlement that provided extensive capital and income support for the parties’ child “T.” Central to the procedural skirmish was the extent of financial disclosure (“vouching”) the father had to furnish in aid of his variation motion. The applicant mother (“D.D.”) sought full, three-year, asset-by-asset vouching. The respondent argued that, because his wealth was vast and he was not pleading inability to pay, only limited income-focused vouching should be required.

Jackson J. took the opportunity to synthesise Rules of the Superior Courts (“RSC”) Order 70A, Practice Direction HC51 and recent case-law on the so-called “millionaire’s defence.” She articulated a clear yardstick: the disclosure/vouching demanded in variation applications must be “appropriate and necessary having regard to the circumstances of the particular case.” That calibration – not rote adherence to a three-year asset trawl – became the touchstone of the ruling.

2. Summary of the Judgment

• The court treated the motion as confined to periodic (ongoing) maintenance, not to lump-sum or capital provisions previously executed.
• The respondent had already sworn a compliant Affidavit of Means; the debate concerned vouching thereof.
• Invoking Order 70A r.6(4) RSC and PD HC51, Jackson J. ruled that she must order only the vouching that is appropriate and necessary.
• Because the variation was not based on the father’s alleged inability to pay but on alleged excess relative to the child’s needs, income documentation and light-touch asset verification sufficed; a “deep trawl” into worldwide assets was disproportionate.
• Item-by-item, the court directed limited extra vouching (e.g. bank statements, proof of salary receipt, tax returns) and refused broader categories (e.g. corporate minutiae, exhaustive asset tracing).
• The court emphasised privacy, cost-proportionality and timeliness, directed both parties to update vouching within three months of hearing, and reserved costs.

3. Analysis

3.1 Precedents Cited and Their Influence

1. XC v YC [2023] IEHC 671 – O’Donnell J. held that an Affidavit of Means is mandatory despite vast wealth and that Order 70A’s remedies address default, not waiver. Jackson J. relied on this to confirm the obligation to swear the affidavit (already fulfilled) and to frame the debate as one solely about vouching scope.
2. Y v X [2024] EWFC 4 and the English line of authority starting with Thyssen-Bornemisza (No 2) [1985] FLR 1069 – Peel J. described the “millionaire’s defence,” warning that even the ultra-wealthy usually must provide some disclosure. Jackson J. imported the rationale (scale of wealth, enforceability, budget reasonableness) while noting Ireland’s distinct statutory regime.
3. Re A (A Child: Financial Provision) [2014] EWCA Civ 1577 – cited indirectly through Y v X for the proposition that the extent of wealth informs reasonableness of claims.

3.2 Legal Reasoning of the Court

The reasoning moved through three statutory/procedural layers:

1. Statutory Framework – Guardianship of Infants Act 1964 and Family Law (Maintenance of Spouses and Children) Act 1976 empower the court to vary maintenance while prioritising the child’s welfare.
2. Rules of Court – Order 70A r.6 mandates an Affidavit of Means and permits a dispute mechanism (r.6(4)) under which the court may order “discovery or any order… appropriate and necessary.” This provides an express proportionality test.
3. Practice Direction HC51 – sets a general three-year vouching rule but recognises variability (“depending on the circumstances”).

Synthesising those layers, Jackson J. articulated a balancing exercise considering:

• Relevance of information to the disputed issue (here, the child’s needs and parties’ incomes).
• Privacy rights and absence of marital status (non-spousal claim).
• Cost and delay inherent in deep forensic exercises.
• Historic disclosure at the 2021 settlement (assuming adequacy).

Applying that matrix, she ordered focussed vouching of income streams, confirmatory asset evidence and narrative explanations on certain transfers, while rejecting fishing expeditions into company affairs, luxury expenditure and third-party accounts.

3.3 Impact on Future Case-Law and Practice

• Clarifies Scope of “Millionaire’s Defence” in Ireland – Wealth does not excuse disclosure, but it may justify calibrated disclosure. The court endorsed an intermediate path between full waiver and full three-year vouching.
• Establishes “Tailored-Disclosure Standard” – Practitioners now have a High Court authority to argue proportionality by reference to the appropriate and necessary yardstick, especially in maintenance variation (as opposed to divorce/judicial-separation) proceedings.
• Encourages Early Case Management – Jackson J.’s itemised approach demonstrates that granular disclosure disputes can, and should, be resolved at case-management, reducing satellite litigation.
• Protects Financial Privacy – The judgment recognises privacy as a legitimate counterweight where parties are not spouses and the application is narrow.
• Influences Drafting of Motions & Affidavits – Counsel must ensure that grounding affidavits mirror the reliefs sought; wide-ranging motions unsupported by focused affidavits may be curtailed.

4. Complex Concepts Simplified

Affidavit of Means

A sworn statement listing a party’s income, assets, debts and expenses. In family law it provides the factual basis for maintenance or property orders.

Vouching

The documentary proof (bank statements, payslips, deeds, tax returns) that corroborates figures in an Affidavit of Means.

Millionaire’s Defence

An argument that, because a party’s wealth is indisputably vast, exhaustive financial disclosure is unnecessary. Irish courts treat it skeptically: some disclosure is always required.

Variation Application

A request to change (increase, reduce, suspend) an existing maintenance order or settlement due to alleged change in circumstances or mis-alignment with the child’s needs.

“Appropriate and Necessary” Test

The proportionality standard in Order 70A r.6(4) RSC allowing the court to limit or compel vouching based on what is relevant to the live issues, balanced against privacy, cost and fairness.

5. Conclusion

D.D v N.B.T. crystallises an important procedural principle in Irish family law: while comprehensive financial disclosure is foundational, its extent must match the purpose of the application. Jackson J.’s judgment supplies a workable template for courts and practitioners to weigh relevance, privacy and proportionality when ordering vouching, especially in child-maintenance variation cases where the payor’s ability to pay is not contested. The decision tempers the rigid application of three-year vouching norms and limits opportunistic deployment of the “millionaire’s defence,” thereby promoting efficient, child-focused justice.