Minimal Viable Estate

Introduction#

Implementing INHERIT need not be an all-or-nothing exercise. The principle of minimal viable data — the smallest amount of structured data that still delivers measurable value — underpins INHERIT’s adoption model. INHERIT defines four Minimal Viable Estate (MVE) levels. Each level represents a distinct entry point with its own use case, implementation effort, and conformance outcome.

The four levels form an adoption ladder: implementers can ship at Level 0, validate with real users, and climb the ladder as confidence grows. Each rung is a complete, schema-valid INHERIT document — not a draft or a partial representation. Every level can be produced, validated, and exchanged with any conformant INHERIT tool.

Level 0 — Testator Only#

Use case: Onboarding. A user has just created an account. You know who they are but nothing else about their estate.

What it contains:

• The testator’s given name, family name, and date of birth
• Domicile (country and legal subdivision)
• Status: planning
• All required arrays present but empty

What it does not contain: assets, beneficiaries, executors, bequests, or any jurisdiction extension.

Required fields at this level:

Fixture: examples/fixtures/mve-level-0-testator-only.json

Level 1 — Simple Will#

Use case: Straightforward estate. A testator has a single executor, one or more beneficiaries, and at least one asset. This is the minimum useful estate — it captures who gets what.

What it contains (in addition to Level 0):

• A second person in the people array with roles: ["executor"]
• An executor object in the executors array referencing that person
• At least one beneficiary (roles: ["beneficiary"]) in the people array
• At least one asset in the assets array (e.g. a savings account, category: "financial")
• At least one bequest in the bequests array, linking the asset description to the beneficiary
• A jurisdiction extension declaration (e.g. uk-england-wales)

What it does not contain: properties (real estate), kinship relationships, guardians, trusts, or tax position calculations.

Fixture: examples/fixtures/mve-level-1-simple-will.json

The fixture tells a coherent story: Jane Thompson appoints her husband David as executor and leaves her Nationwide savings account to her daughter Sophie.

Level 2 — Full Domestic Estate#

Use case: Solicitor-prepared estate. A complete single-jurisdiction estate with residential property, multiple assets, explicit kinship relationships, guardian appointments, and a conformance declaration at level_2.

What it contains (in addition to Level 1):

• Residential property in the properties array
• Multiple assets across categories (financial, personal, digital)
• Kinship relationships (parent/child, marriage)
• Guardian appointment where minor children are present
• Conformance declaration with completenessScore
• applicationState block with completeness checklist and recommended actions
• Tax position estimate

Fixture: examples/fixtures/english-family-estate.json

Level 3 — Cross-Border Estate#

Use case: International or high-net-worth estate. The testator holds assets or has family connections across multiple jurisdictions, requiring multiple extensions and dual succession instruments.

What it contains (in addition to Level 2):

• Multiple jurisdiction extensions (e.g. uk-england-wales and islamic-succession)
• Dual will or equivalent multi-instrument arrangement (willType: "dual")
• Digital assets (category: "digital")
• Assets in multiple currencies
• Religious or cultural succession considerations
• Detailed provenance metadata

Fixture: examples/fixtures/fatima-al-rashid-islamic-digital-estate.json

Adoption Ladder#

Notes on conformance levels:

• Level 1 conformance requires a valid schema-conformant document with testator identity and domicile. Both MVE Level 0 and Level 1 meet this threshold.
• Level 2 conformance additionally requires executor appointment, at least one asset, and a bequest. MVE Level 1 achieves Level 2 conformance once a conformance block is declared.
• Conformance declarations are optional in the document structure but required for interoperability with conformance-aware tools such as the INHERIT Conformance Kit .

The ladder is not prescriptive — implementers may choose to skip levels or merge them. The purpose is to make it clear that any level of INHERIT adoption is better than none, and that a Level 0 document is a genuine contribution to the open estate data ecosystem.