Japan's postal rulebook has fixed the ceiling on a standard letter at ¥110 for years. Under draft rules the Ministry of Internal Affairs and Communications opened for public comment on August 20, that number disappears from the regulation entirely. In its place: an approval system in which Japan Post must justify any new cap using a prescribed cost formula, rather than regulators simply setting a figure in the rulebook.
The change follows an amendment to the Postal Law (Act No. 42 of 2026), promulgated on June 19, that let the company adjust postal rates more flexibly as its costs and market conditions shift. The draft examination standard spells out how any proposed cap will be checked: it must not exceed a level that covers efficient operating costs plus a reasonable profit, calculated over a three-year cost period using the company's own financial statements, with logistics and other non-postal businesses stripped out.
| Element | New Rule |
|---|---|
| Standard letter rate cap | No longer fixed at ¥110 in regulation; must be approved case by case |
| Cost calculation method | "Full-cost" formula covering postal operations only, excluding Japan Post's other businesses such as logistics |
| Cost calculation period | Three years |
| Rate of return | Weighted average of an equity return rate and a debt return rate, blended 30:70 |
| Standard processing time (private courier rate-cap filings) | Two to five months |
| Public comment window | August 20 to September 18, 2026 |
The profit component is built like a regulated-utility formula: a "rate base" of fixed assets, plus 12.5 percent allowances for operating costs, inventories and goods, multiplied by a blended cost of capital. That capital cost weights an equity return rate and a debt return rate 30:70, with the equity figure benchmarked against bond yields and the average return on equity across all industries excluding Japan Post itself, adjusted by a beta drawn from five years of Japan Post Holdings' share-price data against the TOPIX. It is a wonkish exercise, but the practical upshot is that regulators will now scrutinize Japan Post's actual cost base, including labour, fuel, vehicle maintenance and facility charges, each escalated using published price indices, rather than defending a static yen figure.
The same approval logic is being extended to private correspondence-delivery operators, whose standard mail items under 25 grams currently face the identical ¥110 ceiling. A parallel draft sets the standard processing time for that courier rate-cap approval at two to five months, longer than the one-to-two months allotted for approving a courier's terms of service. The packet does not specify an equivalent standard processing time for Japan Post's own rate-cap approval under the Postal Law.
For businesses that rely on bulk mail, invoicing, or direct-mail marketing in Japan, the mechanics matter more than the headline. Removing a fixed cap does not itself raise postage; it opens a formal channel for Japan Post to request higher caps tied to its own falling mail volumes and rising unit costs, subject to regulatory approval rather than a simple rule change. The ministry is taking comments through September 18, 2026, ahead of the amended law's implementation date, which has not yet been fixed in the draft texts.