Name: OpenAccountants MCP Server
Author: OpenAccountants

openaccountants/skills/jp-social-insurance.md

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1	---
2	name: jp-social-insurance
3	description: >
4	Use this skill whenever asked about Japanese National Health Insurance (NHI) or National Pension for self-employed individuals. Trigger on phrases like "NHI", "kokumin kenko hoken", "kokumin nenkin", "national pension Japan", "health insurance freelancer Japan", "social insurance self-employed Japan", or any question about NHI premiums, pension contributions, or social insurance obligations for sole proprietors in Japan. Covers NHI income-based calculation, National Pension fixed monthly amount, payment schedules, and reduction/exemption rules. ALWAYS read this skill before touching any Japanese social insurance work.
5	version: 2.0
6	jurisdiction: JP
7	tax_year: 2025
8	category: international
9	---
10
11	# Japan NHI + National Pension -- Self-Employed Skill v2.0
12
13	## Section 1 -- Quick reference
14
15	Read this whole section before computing anything.
16
17	\| Field \| Value \|
18	\|---\|---\|
19	\| Country \| Japan \|
20	\| Jurisdiction Code \| JP \|
21	\| Primary Legislation \| National Health Insurance Act; National Pension Act \|
22	\| Supporting Legislation \| Long-Term Care Insurance Act; Local Tax Act \|
23	\| Tax Authority \| Municipal governments (NHI); Japan Pension Service (National Pension) \|
24	\| Tax Year \| FY 2025 (April 2025 -- March 2026) \|
25	\| Currency \| JPY only \|
26	\| Contributor \| Open Accountants Community \|
27	\| Validated By \| Pending -- requires sign-off by a Japanese tax accountant or social insurance labour consultant \|
28	\| Validation Date \| Pending \|
29	\| Skill Version \| 2.0 \|
30	\| Confidence Coverage \| Tier 1: National Pension fixed amount, NHI component structure, payment schedules, caps. Tier 2: NHI municipal rate variations, reduction eligibility, partial-year calculations. Tier 3: disability pension, survivors pension, voluntary additional pension. \|
31
32	National Pension (FY 2025):
33
34	\| Item \| Amount \|
35	\|---\|---\|
36	\| Monthly premium \| JPY 17,510 \|
37	\| Annual total \| JPY 210,120 \|
38	\| Category 1 insured \| Self-employed, freelancers, students, unemployed aged 20-59 \|
39	\| Tax treatment \| Fully deductible as social insurance premium deduction \|
40
41	NHI component structure:
42
43	\| Component \| Purpose \| Applies To \|
44	\|---\|---\|---\|
45	\| Medical \| Basic health insurance \| All NHI enrollees \|
46	\| Support \| Elderly health system support \| All NHI enrollees \|
47	\| Long-term care \| Long-term care insurance \| Ages 40-64 only \|
48
49	NHI annual caps (FY 2025):
50
51	\| Component \| Annual Cap \|
52	\|---\|---\|
53	\| Medical \| JPY 650,000 \|
54	\| Support \| JPY 240,000 \|
55	\| Long-term care \| JPY 170,000 \|
56	\| Total maximum \| JPY 1,060,000 \|
57
58	NHI sub-elements per component:
59
60	\| Sub-Element \| Basis \| Typical Range \|
61	\|---\|---\|---\|
62	\| Income-based \| Prior-year income minus JPY 430,000 base deduction \| 5-12% (varies by municipality) \|
63	\| Per-capita \| Fixed amount per enrolled person \| JPY 20,000-60,000/year \|
64	\| Per-household \| Fixed amount per household \| JPY 0-30,000/year (some omit) \|
65	\| Asset-based \| Fixed-asset tax \| Being phased out \|
66
67	Low-income reductions (NHI per-capita/per-household only):
68
69	\| Reduction \| Household Income Threshold (2025) \|
70	\|---\|---\|
71	\| 70% reduction \| JPY 430,000 + (JPY 100,000 x earners beyond 1) \|
72	\| 50% reduction \| JPY 430,000 + JPY 295,000 x insured + (JPY 100,000 x earners beyond 1) \|
73	\| 20% reduction \| JPY 430,000 + JPY 545,000 x insured + (JPY 100,000 x earners beyond 1) \|
74
75	Conservative defaults:
76
77	\| Ambiguity \| Default \|
78	\|---\|---\|
79	\| Unknown municipality \| Flag for reviewer -- cannot compute NHI without municipal rates \|
80	\| Unknown prior-year income \| Use JPY 0 (minimum NHI, possible pension exemption) \|
81	\| Unknown age \| Assume under 40 (no long-term care component) \|
82	\| Unknown shakai hoken status \| Assume NOT enrolled (NHI applies) \|
83
84	---
85
86	## Section 2 -- Required inputs and refusal catalogue
87
88	### Required inputs
89
90	Before computing any social insurance figure, you MUST know:
91
92	1. Residency status -- resident in Japan (non-residents not covered)
93	2. Age -- determines pension category (20-59) and long-term care (40-64)
94	3. Municipality of residence -- NHI rates vary by municipality
95	4. Prior-year income -- NHI premiums based on prior calendar year
96	5. Number of NHI-enrolled household members -- per-capita component per person
97	6. Whether enrolled in any employer health insurance -- employees on shakai hoken excluded from NHI
98	7. Whether any pension exemption or deferral has been granted
99
100	If the client is enrolled in employer-based health insurance, STOP. This skill covers NHI only.
101
102	### Refusal catalogue
103
104	R-JP-SI-1 -- Disability pension. Trigger: client asks about disability pension eligibility or computation. Message: "Disability pension eligibility and computation under the National Pension Act require case-specific assessment. Please escalate to a social insurance labour consultant."
105
106	R-JP-SI-2 -- Survivors pension. Trigger: client asks about survivors pension. Message: "Survivors pension claims are outside this skill's scope. Please escalate to a social insurance labour consultant."
107
108	R-JP-SI-3 -- Voluntary additional pension (Kokumin Nenkin Kikin). Trigger: client asks about additional pension schemes. Message: "Voluntary additional pension schemes require separate analysis. Please escalate to a qualified professional."
109
110	---
111
112	## Section 3 -- Payment pattern library
113
114	This is the deterministic pre-classifier for bank statement entries related to social insurance. Match by case-insensitive substring.
115
116	### 3.1 National Pension debits
117
118	\| Pattern \| Treatment \| Notes \|
119	\|---\|---\|---\|
120	\| NENKIN, PENSION, 年金, 国民年金 \| NATIONAL PENSION PAYMENT \| Monthly premium -- due by end of following month \|
121	\| JAPAN PENSION SERVICE, 日本年金機構 \| NATIONAL PENSION PAYMENT \| Same \|
122	\| 年金前納, ADVANCE PENSION \| ADVANCE PENSION PAYMENT \| 6-month, 1-year, or 2-year advance payment (discounted) \|
123
124	### 3.2 NHI premium debits
125
126	\| Pattern \| Treatment \| Notes \|
127	\|---\|---\|---\|
128	\| NHI, 国民健康保険, 国保, KOKUMIN KENKO \| NHI PREMIUM PAYMENT \| Municipal billing -- typically June to March (10 instalments) \|
129	\| 市区町村, CITY OFFICE, WARD OFFICE \| POSSIBLE NHI PAYMENT \| Verify -- municipalities bill NHI directly \|
130	\| 口座振替 (bank debit) + municipal name \| NHI AUTO-DEBIT \| Auto-debit for NHI premium \|
131
132	### 3.3 Long-term care (embedded in NHI for ages 40-64)
133
134	\| Pattern \| Treatment \| Notes \|
135	\|---\|---\|---\|
136	\| 介護保険, LONG-TERM CARE \| LTCI COMPONENT \| Included in NHI billing for ages 40-64; separate billing for 65+ \|
137
138	### 3.4 Employer health insurance (exclusion trigger)
139
140	\| Pattern \| Treatment \| Notes \|
141	\|---\|---\|---\|
142	\| 健康保険, KENPO, 協会けんぽ \| EMPLOYER HEALTH INSURANCE \| Client is on shakai hoken -- STOP, NHI skill does not apply \|
143	\| 厚生年金, KOSEI NENKIN \| EMPLOYEES PENSION \| Client is on shakai hoken -- STOP \|
144
145	---
146
147	## Section 4 -- National Pension rules
148
149	### 4.1 Category 1 insured (Tier 1)
150
151	Legislation: National Pension Act, Art. 87
152
153	Self-employed individuals, freelancers, students, and unemployed aged 20-59 are Category 1 insured. Monthly premium for FY 2025: JPY 17,510. Annual total: JPY 210,120.
154
155	### 4.2 Payment methods and discounts (Tier 1)
156
157	\| Method \| Discount \|
158	\|---\|---\|
159	\| Monthly \| None \|
160	\| 6-month advance \| ~1% \|
161	\| 1-year advance \| ~2% \|
162	\| 2-year advance \| ~4% \|
163	\| Bank transfer (early debit) \| Slight additional discount \|
164
165	### 4.3 Tax deductibility (Tier 1)
166
167	National Pension premiums are fully deductible as social insurance premium deduction on the income tax return. No cap.
168
169	### 4.4 Exemptions and deferrals (Tier 1 / Tier 2)
170
171	Legislation: National Pension Act, Art. 90
172
173	\| Exemption Type \| Income Threshold (single, approx) \| Payment \|
174	\|---\|---\|---\|
175	\| Full exemption \| Prior-year income <= JPY 670,000 \| JPY 0 \|
176	\| 3/4 exemption \| Income <= ~JPY 930,000 \| 1/4 of standard \|
177	\| 1/2 exemption \| Income <= ~JPY 1,410,000 \| 1/2 of standard \|
178	\| 1/4 exemption \| Income <= ~JPY 1,890,000 \| 3/4 of standard \|
179	\| Payment deferral (under 50) \| Income <= JPY 670,000 \| Deferred \|
180
181	Exemption/deferral reduces future pension benefits. Flag for reviewer if client qualifies.
182
183	---
184
185	## Section 5 -- NHI computation
186
187	### 5.1 NHI computation template (Tier 2)
188
189	Because rates vary by municipality, this is a template. Actual rates must be obtained from the client's municipal office.
190
191	\| Step \| Action \|
192	\|---\|---\|
193	\| 5.1 \| Obtain prior calendar year total income \|
194	\| 5.2 \| Subtract base deduction: JPY 430,000 to get NHI taxable income \|
195	\| 5.3 \| For each component (Medical, Support, Long-term care): multiply by municipal income-based rate \|
196	\| 5.4 \| Add per-capita amount x number of NHI-enrolled household members \|
197	\| 5.5 \| Add per-household flat amount (if municipality charges it) \|
198	\| 5.6 \| Cap each component at statutory maximum \|
199	\| 5.7 \| Sum all three components = annual NHI premium \|
200	\| 5.8 \| Divide by number of instalments (typically 10) \|
201
202	### 5.2 Illustrative rates -- Tokyo 23 Wards (Tier 2)
203
204	\| Component \| Income Rate \| Per-Capita \| Per-Household \|
205	\|---\|---\|---\|---\|
206	\| Medical \| ~7.17% \| ~JPY 42,100 \| JPY 0 \|
207	\| Support \| ~2.42% \| ~JPY 14,400 \| JPY 0 \|
208	\| Long-term care \| ~2.14% \| ~JPY 15,600 \| JPY 0 \|
209
210	These rates are illustrative. Always verify with the specific municipality.
211
212	### 5.3 Low-income reduction (Tier 1)
213
214	Reductions apply only to per-capita and per-household portions, NOT to income-based portion. The 70%/50%/20% reductions are applied automatically based on household income reported to the municipality.
215
216	---
217
218	## Section 6 -- Payment schedules
219
220	### 6.1 NHI (Tier 1)
221
222	\| Detail \| Value \|
223	\|---\|---\|
224	\| Payment period \| Typically June to March (10 instalments) \|
225	\| Due date \| End of each month (varies by municipality) \|
226	\| Methods \| Bank transfer, convenience store, credit card, bank debit \|
227
228	### 6.2 National Pension (Tier 1)
229
230	\| Detail \| Value \|
231	\|---\|---\|
232	\| Payment period \| Monthly, April to March \|
233	\| Due date \| End of the following month \|
234	\| Methods \| Bank transfer, convenience store, credit card, Pay-easy, bank debit \|
235
236	---
237
238	## Section 7 -- Edge case registry
239
240	### EC1 -- Mid-year arrival in Japan (Tier 2)
241	Situation: Client registers as resident in September.
242	Resolution: NHI prorated from month of registration. Pension owed from month of gaining Category 1 status. Prior-year income may be zero, resulting in low NHI and possible pension exemption. Flag for reviewer.
243
244	### EC2 -- Dual income: self-employment + part-time employment (Tier 1)
245	Situation: Client works part-time (under shakai hoken threshold) and freelances.
246	Resolution: If part-time does not provide shakai hoken, client remains on NHI. Both employment and self-employment income included in NHI calculation. Pension remains Category 1.
247
248	### EC3 -- Client turns 40 during year (Tier 1)
249	Situation: Client turns 40 in October.
250	Resolution: Long-term care component starts from the month the client turns 40. NHI premium recalculated mid-year.
251
252	### EC4 -- Client turns 60 during year (Tier 1)
253	Situation: Client turns 60 in March.
254	Resolution: Category 1 obligation ends the month before turning 60. May optionally continue as voluntary insured. Escalate for advice on voluntary continuation.
255
256	### EC5 -- Client has high income but few assets (Tier 1)
257	Situation: Freelancer earns JPY 10,000,000.
258	Resolution: Income-based portion will be high, but each component is capped. Total NHI cannot exceed JPY 1,060,000.
259
260	### EC6 -- Non-payment consequences (Tier 1)
261	Situation: Client has not paid NHI for 12 months.
262	Resolution: Municipality may issue short-validity insurance card or qualification certificate requiring 100% upfront payment. Pension non-payment reduces future benefits and may affect disability pension eligibility.
263
264	---
265
266	## Section 8 -- Reviewer escalation protocol
267
268	When a Tier 2 situation is identified:
269
270	```
271	REVIEWER FLAG
272	Tier: T2
273	Client: [name]
274	Situation: [description]
275	Issue: [what is ambiguous]
276	Options: [possible treatments]
277	Recommended: [most likely correct treatment and why]
278	Action Required: Qualified professional must confirm before advising client.
279	```
280
281	When a Tier 3 situation is identified:
282
283	```
284	ESCALATION REQUIRED
285	Tier: T3
286	Client: [name]
287	Situation: [description]
288	Issue: [outside skill scope]
289	Action Required: Do not advise. Refer to qualified professional. Document gap.
290	```
291
292	---
293
294	## Section 9 -- Test suite
295
296	### Test 1 -- Standard freelancer, mid-range income (Tokyo 23 Wards illustrative)
297	Input: Age 35, single, prior-year income JPY 5,000,000, no other household NHI members.
298	Expected output: NHI taxable income = 5,000,000 - 430,000 = JPY 4,570,000. Medical: ~JPY 369,769. Support: ~JPY 124,994. Long-term care: N/A (under 40). Total NHI: ~JPY 494,763. Pension: JPY 210,120. Total: ~JPY 704,883.
299
300	### Test 2 -- Low-income freelancer qualifying for 70% reduction
301	Input: Age 28, single, prior-year income JPY 300,000.
302	Expected output: NHI taxable income = JPY 0. Income-based = JPY 0. 70% reduction on per-capita. Medical per-capita: JPY 12,630. Support: JPY 4,320. Total NHI: ~JPY 16,950. Pension: full exemption likely.
303
304	### Test 3 -- High earner hitting caps
305	Input: Age 45, single, prior-year income JPY 20,000,000.
306	Expected output: Medical capped at JPY 650,000. Support capped at JPY 240,000. Long-term care capped at JPY 170,000. Total NHI: JPY 1,060,000. Pension: JPY 210,120. Total: JPY 1,270,120.
307
308	### Test 4 -- Mid-year registration
309	Input: Age 30, registers residency in July (9 months).
310	Expected output: NHI prorated x 9/12. Pension: JPY 17,510 x 9 = JPY 157,590.
311
312	---
313
314	## Section 10 -- Prohibitions and disclaimer
315
316	### Prohibitions
317
318	- NEVER assume NHI rates are uniform across Japan -- they vary by municipality and MUST be verified
319	- NEVER omit the long-term care component for clients aged 40-64
320	- NEVER include clients enrolled in employer shakai hoken in NHI calculations
321	- NEVER treat National Pension as optional for Category 1 insured persons aged 20-59 -- it is legally mandatory
322	- NEVER forget that NHI premiums are based on PRIOR-year income, not current-year income
323	- NEVER apply the low-income reduction to the income-based portion -- it applies only to per-capita and per-household portions
324	- NEVER present calculations as definitive -- always label as estimated and direct client to their municipal office or a qualified professional
325
326	### Disclaimer
327
328	This skill and its outputs are provided for informational and computational purposes only and do not constitute tax, legal, or financial advice. Open Accountants and its contributors accept no liability for any errors, omissions, or outcomes arising from the use of this skill. All outputs must be reviewed and signed off by a qualified professional (such as a tax accountant, social insurance labour consultant, or equivalent licensed practitioner in Japan) before filing or acting upon.
329
330	The most up-to-date, verified version of this skill is maintained at [openaccountants.com](https://openaccountants.com). Log in to access the latest version, request a professional review from a licensed accountant, and track updates as tax law changes.
331

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About

Use this skill whenever asked about Japanese National Health Insurance (NHI) or National Pension for self-employed individuals. Trigger on phrases like "NHI", "kokumin kenko hoken", "kokumin nenkin", "national pension Japan", "health insurance freelancer Japan", "social insurance self-employed Japan", or any question about NHI premiums, pension contributions, or social insurance obligations for sole proprietors in Japan. Covers NHI income-based calculation, National Pension fixed monthly amount, payment schedules, and reduction/exemption rules. ALWAYS read this skill before touching any Japanese social insurance work.

JPty-2025

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