Ladder real flows coupons

Inflation-adjusted coupon cash flow paid by ladder holdings in a year.

Field: coupons Unit: US dollars Basis: today's dollars (real) Computed by: Engine Status: Complete chain

Appears in: income-floor (coupon cash flow)

Calculation records

• Ladder cash flows in a year and face outstanding after it Formula record, justified by derivation

  Purpose: The real coupons, maturing principal and outstanding face of a rung set in one year, and the face still outstanding once that year completes.

  Statement: For a rung set and an integer offset k >= 1: coupons = sum over rungs with maturity offset >= k of F·c/100; maturingPrincipal = sum of F over rungs with maturity offset = k; outstandingFace = sum of F over rungs with maturity offset >= k, the maturing rung included so it earns its last coupon and its inflation accretion. ladderRemainingFace(k) = sum of F over rungs with maturity offset > k, the face still outstanding after year k completes. Units: real (today's) dollars. Rounding: none.

  Formula: coupons_k = sum_{m >= k} F_m c_m/100; maturing_k = sum_{m = k} F_m; outstanding_k = sum_{m >= k} F_m; remaining_k = sum_{m > k} F_m

  • k: Year offset from the anchor year (unit: years) (domain: integer k >= 1)
  • F_m: Real face of the rung maturing at offset m (unit: usd) (domain: F_m >= 0)
  • c_m: Annual coupon rate of that rung (unit: percent/year) (domain: c_m >= 0.125)

  Timing: annual; a rung is outstanding through the year it matures and gone the year after

  Rounding: none

  Limits:

  • Values are real (today's) dollars; the ledger multiplies by its own inflation path to index them
  • ladder-value-annual is the ledger's nominal figure: ladderRemainingFace at the year's offset times the purchase scale and the year's inflation factor (projection/internal/tipsLadderAnnualCashFlow.ts); this record pins the remaining-face half of that product
  • Offsets are whole years by construction; a fractional offset matches no maturity

  Provenance: derived by codex, implemented by claude-subagent.

  Independent review: cursor

  Gates (6 of 6 pass): fixture registers a test: pass; pins resolve: pass; families exist: pass; worksheet exists: pass; mutation receipt exists: pass; provenance independent: pass

  Worksheet: ladder-rung-flows-and-remaining-face.md Mutation receipt: ladder-rung-flows-and-remaining-face.mutation.md

  Evidence tests: ladderMath.evidence.test.ts

  Implemented in: ladderMath.ts

  Is the number of: ladder-real-flows-coupons, ladder-real-flows-maturing-principal

  Feeds: ladder-value-annual

Engine source: engine/src/ladder/ladderMath.ts (LadderRealFlows.coupons)