# Open Social Security

Free, MIT-licensed claiming calculator — every claiming month, priced by present value.

*https://stockmarketstack.com/tools/open-social-security · Retirement & FIRE Calculators*

## Facts

### At a glance

| Field | Value |
| --- | --- |
| Vendor | Open Social Security |
| Category | Retirement & FIRE Calculators |
| Job | retirement |
| Website | https://opensocialsecurity.com |
| Pricing model | open-source |
| Free tier | true |
| Open source | true |
| Licence | MIT |
| Self-hosted | true |
| Tested hands-on | false |
| Last updated | 2026-10-04 |

### Coverage

| Field | Value |
| --- | --- |
| Asset classes | none |
| Markets | us |
| Works outside the US | false |
| Data latency | none |
| Platforms | web |
| AI features | none |

### Interfaces

| Field | Value |
| --- | --- |
| API | false |
| Webhooks | false |
| Scripting | none |
| Python | false |
| Spreadsheet add-in | false |
| MCP server | false |

### Capabilities

Yes: none

No: charting, screening, scanning, backtesting, automation, live_trading, paper_trading, portfolio_tracking, broker_import, tax_reporting, alerts, news, options_analysis

*Verified: pricing 2026-10-04; capabilities 2026-10-04; coverage 2026-10-04.*

## What it is

Open Social Security is a free web calculator for one question: at what age should you, or you
and your spouse, file for Social Security retirement and spousal benefits? Mike Piper, a CPA in
St. Louis and author of the Oblivious Investor blog, wrote it and publishes it under the MIT
licence; Brian Courts contributed the colour-coded graph of how good each filing date is. There
is no account and nothing for sale.

The method is an expected present value. For a single person it assumes filing at each possible
month from 62 to 70, computes the resulting annual benefit, weights each year up to age 115 by
the probability of being alive, discounts that back at a real discount rate, and sums. The month
with the highest present value is reported, with the value itself. Claiming dates already in the
past are dropped. For a couple it adds spousal and survivor benefits, weights each year by the
probability that only A, only B or both are alive, and searches every combination of both
spouses' retirement and spousal filing dates.

Everything is in real, inflation-adjusted dollars. The default discount rate is the current
20-year TIPS yield, fetched from the Treasury's daily real yield curve when the page loads, with
a hard-coded 1% if that request fails; you can overwrite it. Mortality defaults to the SSA
period life table, roughly average health. Four Society of Actuaries 2017 CSO tables are offered
for better or worse health, from non-smoker super-preferred to smoker residual standard — and you
can instead enter an assumed age at death.

Inputs are the primary insurance amount from your SSA statement, date of birth, gender and
marital status — single, married, divorced or widowed — plus optional situations: still working
under full retirement age, which triggers the earnings test; currently on disability; children
under 19 or disabled before 22; an already-filed benefit; and a possible future benefit cut.
The README lists further rules it handles — deemed filing for those born before 2 January 1954,
voluntary suspension, family maximum, child-in-care spousal benefits and retroactive
applications.

## Pricing

Free. No account and no paid tier. The About page carries an affiliate link to the author's
own book on Social Security, which is the whole of its commercial side.

## Data & coverage

US Social Security only. The calculator's only external data are the TIPS yield and the
mortality tables; the benefit figure is the one you type in.

The README still lists the Windfall Elimination Provision and Government Pension Offset among
the factors it handles. Both were repealed by the Social Security Fairness Act, signed on 5
January 2025, and the strings for them are absent from the live site's JavaScript bundle read on
4 October 2026 — so the README describes a model the site no longer runs.

## Integrations

None. Inputs can be carried in the URL — the app reads PIA, dates of birth, gender, mortality
table, discount rate and benefit-cut settings from query parameters — so a scenario can be
shared as a link. It can also be run locally: the
repository is an Angular 20 project with the standard `ng serve` and `ng build` scripts.

## Limitations

- **One decision only.** No taxes, no accounts, no withdrawals, no spending model; it does not
  know whether you can afford to wait.
- **Maximises expected value, not insurance.** By its own author's note, a later claim that
  protects against a very long life can be the better choice even when it is not the top result.
- **The answer is only as good as the PIA you enter** — the tool does not read your earnings
  record, and the PIA changes with new earnings and indexing.
- **No releases or changelog.** Changes are commits to master; the README lags the code.
- **Benefit-cut modelling is a single step** at one year and one percentage, off by default.

## Alternatives

[MaxiFi Planner](https://stockmarketstack.com/tools/maxifi-planner) runs a Social Security optimiser inside a full lifetime
plan, so a later claiming age is weighed against the gap before benefits start; its maker also
sells a focused claiming tool, Maximize My Social Security. [Pralana Gold](https://stockmarketstack.com/tools/pralana-gold)
and [Boldin](https://stockmarketstack.com/tools/boldin) model claiming age inside a whole retirement projection, with
taxes.

## FAQ

### How does Open Social Security decide which claiming age is best?

For each possible claiming month from 62 to 70, it computes the annual benefit, multiplies each year's amount by the probability of being alive that year up to age 115, discounts it back to a present value at your real discount rate, and sums the result. The month with the highest total is reported. For a couple it does the same over every combination of both spouses' retirement and spousal filing dates, including survivor benefits.

### What does Open Social Security not take into account?

Taxes, and the value of delaying as insurance against a long life. Its own About page says delaying reduces longevity risk and may be preferable even where it does not maximise expected spending, and that tax planning can argue for filing earlier or later. It also ignores the rest of your plan — accounts, withdrawals, spending.

### Is Open Social Security still maintained?

Yes. The repository on GitHub is not archived; its last commit to master on 29 September 2026 was a dependency update, and the last functional fix, on 5 September 2026, corrected the output table in the benefit-cut scenario. It publishes no releases or tags — the live site is the build.

### Can it model a future cut in Social Security benefits?

Yes, as an opt-in assumption. The default leaves benefits intact; ticking the box applies a cut in a year and percentage you can edit, pre-filled at 23% from 2033 and referenced to the 2025 Social Security Trustees Report.

## Also worth comparing

- [Boldin](https://stockmarketstack.com/tools/boldin.md) — A year-by-year US retirement model — accounts, taxes, Social Security, Medicare, housing.
- [cFIREsim](https://stockmarketstack.com/tools/cfiresim.md) — Run a withdrawal plan against every market cycle since 1871 and count how many survived.
- [FI Calc](https://stockmarketstack.com/tools/ficalc.md) — Twelve withdrawal strategies replayed against every US market cycle since 1871.
- [FIREproof](https://stockmarketstack.com/tools/fireproof.md) — The cFIREsim author's second simulator, with the taxes and accounts the first one lacks.
- [MaxiFi Planner](https://stockmarketstack.com/tools/maxifi-planner.md) — Consumption smoothing — solves for the spending level you can hold for life, after taxes.
- [Pralana Gold](https://stockmarketstack.com/tools/pralana-gold.md) — A US retirement model in an Excel workbook — taxes, Roth conversions, Monte Carlo.