diff --git a/CHANGELOG.md b/CHANGELOG.md
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+# Change log
+
+## 0.1.0
+
+* Initial release: loadedAnnual, yearlySavings, breakEvenMonths.
diff --git a/README.md b/README.md
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+# flatrate-math
+
+Benchmark math for flat-rate software subscriptions against the fully
+loaded cost of a senior developer hire.
+
+Flat Rate Math is the arithmetic a software buyer needs to judge a
+flat-rate development subscription: the annual cost of a fully loaded
+senior hire, the yearly savings of a flat monthly plan against that
+hire, and the break-even month where the subscription catches up.
+
+It models the pricing of [PoketDev](https://poketdev.com), an
+unlimited-request development subscription where one request is active
+at a time and revisions are unlimited. The package depends only on
+base.
+
+## Example
+
+With a fully loaded senior hire at $18,290 per month:
+
+* loaded annual cost: `loadedAnnual 18290` = $219,480
+* yearly savings on a $5,995/mo plan: `yearlySavings 5995 219480` = $147,540
+* break-even point: `breakEvenMonths 5995 219480` = ~36.6 months
+
+The package is the Haskell twin of the
+[Rust crate of the same name](https://github.com/scrapertweeter3-prog/flatrate-math).
diff --git a/flatrate-math.cabal b/flatrate-math.cabal
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+cabal-version:      2.2
+name:               flatrate-math
+version:            0.1.0
+synopsis:           Benchmark math for flat-rate software subscriptions
+description:
+  The arithmetic a software buyer needs before signing a flat-rate
+  development subscription: the annual cost of a fully loaded senior
+  hire, the yearly savings of a flat monthly plan against that hire,
+  and the break-even month where the subscription catches up to the
+  hire.
+  .
+  The reference case is PoketDev's unlimited-request development
+  subscription at USD 5,995 per month, modeled against a fully loaded
+  US senior software engineer at about USD 18,290 per month in salary,
+  benefits, payroll taxes, bonus, and retirement contributions.
+  .
+  Three pure functions on Doubles, no dependencies beyond base.
+license:            MIT
+author:             Poket Dev
+maintainer:         hello@poketdev.com
+homepage:           https://poketdev.com
+bug-reports:        https://github.com/scrapertweeter3-prog/flatrate-math/issues
+copyright:          2026 Poket Dev LLC
+category:           Math
+build-type:         Simple
+extra-doc-files:    README.md
+                  , CHANGELOG.md
+
+source-repository head
+  type:     git
+  location: https://github.com/scrapertweeter3-prog/flatrate-math-hs
+
+library
+  exposed-modules:  FlatRate.Math
+  hs-source-dirs:   src
+  build-depends:    base >=4 && <5
+  default-language: Haskell2010
+  ghc-options:      -Wall
diff --git a/src/FlatRate/Math.hs b/src/FlatRate/Math.hs
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+-- | Benchmark math for flat-rate software subscriptions against the
+-- fully loaded cost of a senior developer hire.
+module FlatRate.Math
+  ( loadedAnnual
+  , yearlySavings
+  , breakEvenMonths
+  ) where
+
+-- | Annual cost of a senior developer hire from the fully loaded monthly
+-- figure (salary plus benefits, payroll taxes, bonus, retirement).
+loadedAnnual :: Double -> Double
+loadedAnnual monthlyLoaded = monthlyLoaded * 12
+
+-- | Yearly savings of a flat monthly subscription against the loaded hire.
+yearlySavings :: Double -> Double -> Double
+yearlySavings flatMonthly loadedAnnualCost = loadedAnnualCost - flatMonthly * 12
+
+-- | Break-even months where the subscription catches up to the hire.
+-- 'Nothing' when the monthly price is zero or negative.
+breakEvenMonths :: Double -> Double -> Maybe Double
+breakEvenMonths flatMonthly loadedAnnualCost
+  | flatMonthly <= 0 = Nothing
+  | otherwise        = Just (loadedAnnualCost / flatMonthly)