Description
General rate proration over supplied half-open day-index bounds, without selecting statutory rules.
A policy scenario makes eligibility bases, rates, thresholds, periods, and costs explicit. A calculated share or balance follows those assumptions. It does not select the governing policy or establish what caused an observed program outcome.
General rate proration over supplied half-open day-index bounds, without selecting statutory rules.
When to use this tool
Use it for policy rate phase in year fraction when the required inputs and conventions are already available.
How to use the tool and how it works
- Enter yearStart, nextYearStart, effectiveDay, oldRate, newRate. Use the stated units and boundary conventions.
- Run the calculation. Correct any input error before interpreting a result.
- Read newRateFraction, blendedRate. Inspect any known, defined, inclusion, or boundary flags before interpreting numeric values.
Require nextYearStart>yearStart and effectiveDay within those endpoints. Weight oldRate by the elapsed pre-change span and newRate by the remaining span, returning blendedRate and the newRateFraction.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| yearStart | Year Start | Required. Safe integer. |
| nextYearStart | Next Year Start | Required. Safe integer. |
| effectiveDay | Effective Day | Required. Safe integer. |
| oldRate | Old Rate | Required. Finite number. |
| newRate | New Rate | Required. Finite number. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| newRateFraction | New Rate Fraction | Required. Finite number. |
| blendedRate | Blended Rate | Required. Finite number. |
{
"input": {
"yearStart": 0,
"nextYearStart": 360,
"effectiveDay": 90,
"oldRate": 0.1,
"newRate": 0.2
},
"output": {
"newRateFraction": 0.75,
"blendedRate": 0.175
}
}Limitations and assumptions
- Year boundaries and day indices are supplied; leap years or fiscal calendars are not inferred. A change at yearStart uses all new rate, while one at nextYearStart uses all old rate.
- The field tables describe structural bounds; the mechanics also state cross-field requirements. Malformed input shapes, disallowed keys, and invalid domains cause input errors. Results must remain finite and within the declared output contract. A successful false flag or zero placeholder is distinct from an error.
- Numeric arithmetic uses binary floating point. Exact comparisons have no hidden tolerance or decimal rounding; negative zero is exported as zero. Decimal-text integer operations retain the exactness specifically stated above.
Alternative or Complementary methods
For policy rate phase in year fraction, check the source records and the supplied rule before comparing the result with another method. Consult the applicable authoritative rule when deciding eligibility, legal timing, fees, or obligations.
References
Similar or alternative tools
- Phase In Threshold Support Gap
Compare explicit support with a supplied linear phase-in interval, without policy eligibility advice.
- Policy Discounted One Year Cost
Calculate policy discounted one year cost from explicit caller-supplied inputs.