These are the expenses every Canadian household pays regardless of economic conditions. You cannot substitute, delay, or opt out. When these go up, the cash is simply gone.

Statistics Canada's CPI blends all spending — including discretionary categories like clothing, electronics, and travel — which are flat or falling. The non-negotiable categories above are being systematically averaged down by expenses you can choose not to make.

The basket gap: Official CPI weights shelter at 30% of spending. For a mortgaged household renewing in 2026, shelter is closer to 37–40% of actual cash out. That single reweighting alone adds several percentage points to the real inflation rate.

The mortgage point illusion: Moving from 3% to 4% sounds like a 1% increase. It is a 25% increase in your monthly payment. The percentage-point framing used in every headline dramatically understates the household impact.

Step 1 — Identify non-negotiables only. The RII™ tracks 7 spending categories that every household must pay regardless of income or preference: shelter, groceries, fuel/transport, utilities, debt service, insurance, and phone/internet.

Step 2 — Reweight to actual household spend. Rather than Statistics Canada's economy-wide basket, the RII™ uses spending weights derived from the 2023 Survey of Household Spending, adjusted to reflect mortgaged households in BC — the cohort most exposed to the current price environment.

Step 3 — Apply current price changes. Each category uses the most recent available price change data: Statistics Canada CPI sub-indices for food, energy, and shelter; Bank of Canada rate decisions for mortgage cost; CMHC renewal data for the actual payment shock on renewing households.

Step 4 — Weight and sum. Each category's price change is multiplied by its basket weight. The weighted sum is the RII™ figure.

Step 5 — Dynamic adjustment. When the Bank of Canada changes its overnight rate, the mortgage component updates automatically. The Cast recalculates the RII™ in real time.