How OHA works in Japan
The rent ceiling is a cap, not a payment. OHA reimburses the rent you actually pay, up to the ceiling for your locality and grade. If your lease is below the ceiling you receive your rent; if it is above, you pay the difference out of pocket. That is the key difference from stateside BAH, where the full rate is paid regardless of rent.
The utility allowance is flat. Japan pays ¥112,012 ($732.82) per month with dependents for utilities and recurring maintenance, and 75% of that without dependents. It is paid whether your bills are higher or lower, so efficient housing puts money in your pocket.
MIHA covers move-in costs. The miscellaneous MIHA of ¥65,477 ($428.37) is paid once when you move into private rental housing and is not reduced for members without dependents. Receipt-based MIHA rent and MIHA security payments are separate and handled by the housing office.
Dollar amounts move twice a month. Japan OHA is set in JPY. DTMO converts it to dollars at an official exchange rate ($0.01 per JPY in the current table) that is revised on the 1st and 16th, so your LES amount changes even when the JPY ceiling does not. This page is regenerated from the DTMO tables on the same schedule.
While you are still house-hunting, the TLA calculator covers temporary lodging on arrival, and overseas COLA starts the day you report. For the exact OHA on a specific lease — your rent against the ceiling, in JPY and dollars — use the OHA calculator.
OHA rates in other countries