If high medical care costs were incurred two or more times during the same month in a single household

You can combine copayments for an entire household (Total High-cost Medical Care Benefits)

Even when the copayment for one case for one month is less than the maximum, if members of the same household have made copayments of 21,000 yen or more multiple times in the same month, they can combine those amounts for the purposes of the Cost-Sharing Maximum Amount.
If the total amount exceeds the household’s maximum copayment amount, the excess will be paid by the Health Insurance Society as “Total High-cost Medical Care Benefits”.

The Society also pays its own (additional) benefits (Additional Total High-cost Medical Care Benefits)

When the Society has paid total high-cost medical care benefits, the amount derived by subtracting 20,000 yen per person subject to totalization*1 from the household’s maximum copayment amount will be paid as additional total high-cost medical care benefits.

• *1  If two persons in the household paid medical care costs subject to totalization, the amount of 20,000 yen × 2 persons = 40,000 yen will be subtracted from the household’s maximum copayment amount.

• * In principle, refunds will be remitted about three months after the examination or treatment.
• * Payment may be delayed if receipt of the invoice for medical care costs (rezept) from the medical care institution for costs to be borne by the Health Insurance Society is delayed.
• * In general, this benefit is paid automatically with no procedures required. However, those eligible to receive publicly funded medical assistance from their municipal governments are not eligible for automatic payment. See here for more information.