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Social insurance is a contributory social protection scheme that guarantees protection through an insurance mechanism. People (or their employers) pay contributions before a risk such as old age, unemployment, sickness or disability occurs, the contributions are pooled, and the resulting fund pays benefits only to those affected by the insured contingency. This guide gives the ILO definition, separates social insurance from social assistance and commercial insurance, maps it to the branches of ILO Convention No. 102, and works through an illustrative contribution and benefit calculation.
Definition in one paragraph
The International Labour Organization (ILO) glossary defines a social insurance scheme as a contributory social protection scheme built on three elements: (a) the payment of contributions before the insured contingency occurs; (b) the sharing or “pooling” of risk; and (c) the notion of a guarantee. The contributions paid by or for insured people are pooled, and the fund covers the expenses of the individuals affected by the relevant contingency (ILO, 2024, Annex, read 2026-11-11). Because it is contributory, contributions made by protected persons directly determine entitlement to benefits. The ILO also notes that social insurance schemes are the most common form of contributory social security schemes and, unlike commercial insurance, are not profit-oriented; they rest on solidarity among members.
Social insurance vs social assistance vs private insurance
The ILO distinguishes schemes by how they are financed and how entitlement is established. The table uses only the ILO’s own descriptions.
| Feature | Social insurance | Social assistance | Commercial insurance |
|---|---|---|---|
| Who it targets | Insured people who contribute (directly or through an employer) | Vulnerable groups, especially households living in poverty | Policyholders |
| Basis of entitlement | Contributions determine entitlement; benefits depend on contribution history and earnings | Need; most schemes are means-tested | Contract |
| Financing | Contributions by protected persons and employers, pooled into a fund | Taxes or other State revenues (non-contributory) | Premiums |
| Purpose | Not profit-oriented; solidarity among members | Poverty alleviation and basic security | Profit-oriented |
Source: ILO World Social Protection Report 2024–26, Annex glossary, and ILO FAQ on Convention No. 102 (both read 2026-11-11). The ILO states that non-contributory, tax-financed schemes may be universal, categorical or means-tested, and that their benefits are often lower than contributory ones.
Social insurance vs social security
Social security is the wider term. Social insurance is one contributory way of delivering it, alongside non-contributory, tax-financed schemes. Many searchers use the two terms interchangeably, but in ILO usage social insurance describes a financing and entitlement design, while social security describes the whole set of measures that secure protection through cash or in-kind benefits.
Which risks does social insurance cover? The nine branches of ILO Convention No. 102
The Social Security (Minimum Standards) Convention, 1952 (No. 102) sets out nine branches of social security: medical care, sickness, unemployment, old age, employment injury, family, maternity, invalidity, and survivors (death of the breadwinner). A State may ratify it if it covers at least three of the branches, at least one of which must be unemployment, old age, employment injury, invalidity or survivors’ benefits (ILO FAQ on C102, read 2026-11-11). Social insurance is a common vehicle for these branches, but the Convention is about the protection provided, not a single financing method.
Worked example (illustrative numbers)
The figures below are invented round numbers chosen to show the arithmetic. They do not describe any country, scheme or real contribution rate.
Suppose a worker earns 40,000 per year. The scheme sets a total contribution rate of 10% of earnings, split 5% paid by the worker and 5% by the employer.
- Contribution per insured worker: 40,000 × 0.10 = 4,000 per year (worker share 2,000; employer share 2,000).
- Pooled fund: 1,000 insured workers × 4,000 = 4,000,000 per year.
- Benefits paid (assumed): 3,600,000 in the same year across all insured contingencies.
- Benefit-to-contribution ratio: 3,600,000 ÷ 4,000,000 = 0.90.
- Annual balance: 4,000,000 − 3,600,000 = +400,000.
- Replacement rate for one claimant: if a claimant receives a benefit of 24,000 per year against prior earnings of 40,000, the rate is 24,000 ÷ 40,000 = 0.60, or 60%.
Interpretation: reading the results
| Measure | Result in the example | What it tells you |
|---|---|---|
| Benefit-to-contribution ratio | 0.90 | Below 1: current benefit spending is less than current contribution income in that year. Above 1: spending exceeds contributions. |
| Annual balance | +400,000 | Positive: surplus for the year. Negative: deficit that must be met from reserves or other sources. |
| Replacement rate | 60% | Share of prior earnings that the benefit replaces for that claimant. |
These are arithmetic indicators, not verdicts on a scheme’s health: a single year’s ratio says nothing about long-run financing, demographics or benefit rules.
Assumptions and common mistakes
- Treating social insurance as the same as social assistance. Entitlement under social insurance comes from contributions; social assistance is typically means-tested and tax-financed.
- Treating it as commercial insurance. The ILO describes it as not profit-oriented and based on solidarity among members.
- Ignoring who pays. Contributions can be paid by the protected person, by the employer, or both; check which a source means.
- Using social security and social insurance interchangeably in a methods section or data dictionary. Define the term you use.
- Importing example rates. The 10%, 5% and 60% above are illustrative only. For real rates, cite the national scheme’s own documentation.
How to cite the definition (APA 7th)
International Labour Organization. (2024). World social protection report 2024–26: Universal social protection for climate action and a just transition. ILO. https://webapps.ilo.org/static/english/reports/flagship/world_social_protection_report_2024-26/Annex.html
For measurement work, define the contributory scheme operationally in your codebook; see our guides on sampling methods and descriptive research when you are estimating coverage from survey data.
How to calculate it in Excel, R or Python
Excel
A1: earnings 40000
A2: total rate 0.10
A3: insured workers 1000
A4: benefits paid 3600000
A5: contributions =A1*A2*A3 (4,000,000)
A6: ratio =A4/A5 (0.90)
A7: balance =A5-A4 (400,000)
A8: replacement =24000/A1 (0.60)R
earnings <- 40000; rate <- 0.10; n <- 1000; benefits <- 3600000
contrib <- earnings * rate * n # 4e+06
ratio <- benefits / contrib # 0.9
balance <- contrib - benefits # 400000
repl <- 24000 / earnings # 0.6Python
earnings, rate, n, benefits = 40000, 0.10, 1000, 3_600_000
contrib = earnings * rate * n # 4000000.0
ratio = benefits / contrib # 0.9
balance = contrib - benefits # 400000.0
repl = 24000 / earnings # 0.6For spreadsheet statistics beyond this arithmetic, see how to find a correlation coefficient in Excel.
FAQ
What is social insurance in simple terms?
A contributory scheme in which people pay in before a risk occurs, the money is pooled, and benefits go to those who experience the insured event, such as old age, unemployment or invalidity.
Is social insurance the same as social security?
No. Social security covers all measures providing benefits to secure protection; social insurance is the most common contributory form within it (ILO).
How is social insurance different from social assistance?
Social insurance entitlement depends on contributions and earnings history. Social assistance targets vulnerable groups, especially households in poverty, and is mostly means-tested.
Is social insurance profit-oriented?
The ILO states that it is not, unlike commercial insurance, and rests on solidarity among members.
Sources
- International Labour Organization. (2024). World social protection report 2024–26, Annex (glossary). https://webapps.ilo.org/static/english/reports/flagship/world_social_protection_report_2024-26/Annex.html (read 2026-11-11)
- International Labour Organization. Frequently asked questions: Social Security (Minimum Standards) Convention, 1952 (No. 102). https://www.ilo.org/frequently-asked-questions-social-security-minimum-standards-convention (read 2026-11-11)
