diff --git a/lib/incidents/dosh.ts b/lib/incidents/dosh.ts
new file mode 100644
index 0000000..b9bcba1
--- /dev/null
+++ b/lib/incidents/dosh.ts
@@ -0,0 +1,49 @@
+export type DoshObligation = {
+  requires_jkkp6: boolean
+  requires_jkkp7: boolean
+  requires_jkkp8: boolean
+  requires_immediate_notification: boolean
+  reasons: string[]
+}
+
+export function computeDoshObligation(incident: {
+  is_fatality: boolean
+  is_serious_bodily_injury: boolean
+  is_dangerous_occurrence: boolean
+  is_occupational_disease: boolean
+  lost_days: number | null
+}): DoshObligation {
+  const reasons: string[] = []
+  let requires_jkkp6 = false
+  let requires_jkkp7 = false
+  let requires_jkkp8 = false
+  let requires_immediate_notification = false
+
+  if (incident.is_fatality) {
+    reasons.push('Fatality — NADOPOD 2004 s.9(1)(a)')
+    requires_jkkp6 = true
+    requires_jkkp7 = true
+    requires_immediate_notification = true
+  }
+  if (incident.is_serious_bodily_injury) {
+    reasons.push('Serious bodily injury — NADOPOD 2004 s.9(1)(b)')
+    requires_jkkp6 = true
+    requires_jkkp7 = true
+  }
+  if (incident.is_dangerous_occurrence) {
+    reasons.push('Dangerous occurrence — NADOPOD 2004 s.9(1)(c)')
+    requires_jkkp6 = true
+    requires_jkkp7 = true
+  }
+  if ((incident.lost_days ?? 0) >= 4) {
+    reasons.push('Lost-time injury ≥4 days — NADOPOD 2004 s.9(1)(d)')
+    requires_jkkp6 = true
+    requires_jkkp7 = true
+  }
+  if (incident.is_occupational_disease) {
+    reasons.push('Occupational disease — NADOPOD 2004 s.11')
+    requires_jkkp8 = true
+  }
+
+  return { requires_jkkp6, requires_jkkp7, requires_jkkp8, requires_immediate_notification, reasons }
+}
diff --git a/tests/lib/incidents/dosh.test.ts b/tests/lib/incidents/dosh.test.ts
new file mode 100644
index 0000000..c2acc85
--- /dev/null
+++ b/tests/lib/incidents/dosh.test.ts
@@ -0,0 +1,78 @@
+import { describe, it, expect } from 'vitest'
+import { computeDoshObligation } from '@/lib/incidents/dosh'
+
+const base = {
+  is_fatality: false,
+  is_serious_bodily_injury: false,
+  is_dangerous_occurrence: false,
+  is_occupational_disease: false,
+  lost_days: null,
+}
+
+describe('computeDoshObligation', () => {
+  it('returns no obligations for minor incident', () => {
+    const result = computeDoshObligation(base)
+    expect(result.requires_jkkp6).toBe(false)
+    expect(result.requires_jkkp7).toBe(false)
+    expect(result.requires_jkkp8).toBe(false)
+    expect(result.requires_immediate_notification).toBe(false)
+    expect(result.reasons).toHaveLength(0)
+  })
+
+  it('fatality triggers jkkp6, jkkp7, immediate notification', () => {
+    const result = computeDoshObligation({ ...base, is_fatality: true })
+    expect(result.requires_jkkp6).toBe(true)
+    expect(result.requires_jkkp7).toBe(true)
+    expect(result.requires_immediate_notification).toBe(true)
+    expect(result.requires_jkkp8).toBe(false)
+    expect(result.reasons).toContain('Fatality — NADOPOD 2004 s.9(1)(a)')
+  })
+
+  it('serious bodily injury triggers jkkp6 + jkkp7, not immediate', () => {
+    const result = computeDoshObligation({ ...base, is_serious_bodily_injury: true })
+    expect(result.requires_jkkp6).toBe(true)
+    expect(result.requires_jkkp7).toBe(true)
+    expect(result.requires_immediate_notification).toBe(false)
+    expect(result.reasons).toContain('Serious bodily injury — NADOPOD 2004 s.9(1)(b)')
+  })
+
+  it('dangerous occurrence triggers jkkp6 + jkkp7', () => {
+    const result = computeDoshObligation({ ...base, is_dangerous_occurrence: true })
+    expect(result.requires_jkkp6).toBe(true)
+    expect(result.requires_jkkp7).toBe(true)
+    expect(result.requires_immediate_notification).toBe(false)
+    expect(result.reasons).toContain('Dangerous occurrence — NADOPOD 2004 s.9(1)(c)')
+  })
+
+  it('occupational disease triggers jkkp8 only', () => {
+    const result = computeDoshObligation({ ...base, is_occupational_disease: true })
+    expect(result.requires_jkkp8).toBe(true)
+    expect(result.requires_jkkp6).toBe(false)
+    expect(result.requires_jkkp7).toBe(false)
+    expect(result.reasons).toContain('Occupational disease — NADOPOD 2004 s.11')
+  })
+
+  it('4+ lost days triggers jkkp6 + jkkp7', () => {
+    const result = computeDoshObligation({ ...base, lost_days: 4 })
+    expect(result.requires_jkkp6).toBe(true)
+    expect(result.requires_jkkp7).toBe(true)
+    expect(result.reasons).toContain('Lost-time injury ≥4 days — NADOPOD 2004 s.9(1)(d)')
+  })
+
+  it('3 lost days does NOT trigger JKKP reporting', () => {
+    const result = computeDoshObligation({ ...base, lost_days: 3 })
+    expect(result.requires_jkkp6).toBe(false)
+    expect(result.requires_jkkp7).toBe(false)
+  })
+
+  it('multiple flags accumulate reasons', () => {
+    const result = computeDoshObligation({
+      ...base,
+      is_fatality: true,
+      is_occupational_disease: true,
+    })
+    expect(result.requires_jkkp6).toBe(true)
+    expect(result.requires_jkkp8).toBe(true)
+    expect(result.reasons).toHaveLength(2)
+  })
+})