Could banks start charging savers if the BoJ cut rates?

Recent suggestions that the Bank of Japan will cut its policy rate have fuelled speculation that Japanese banks might be forced to start passing on negative interest rates to savers. But given that Japan’s city and regional banks do not have excess reserves at the BoJ subject to the negative rate, we think that would only happen if the BoJ decided to charge negative interest on other “tiers”, which seems unlikely.