Consider a family whose mother was hospitalized for over three months at a tertiary general hospital last year. When organizing receipts by date after discharge, a point where the flow breaks can be found. The covered-item out-of-pocket payments that steadily accumulated during the first few weeks of hospitalization stop increasing at a certain point. Meanwhile, receipts for non-covered items, such as private room charges and some test fees, continue to be issued. However, the excess amount over the out-of-pocket maximum shown on this year's National Health Insurance refund inquiry screen is far smaller than the family expected.

This difference is easily understood by comparing two patients in the same income bracket who spent the same amount on covered treatment. One was hospitalized for a long time at a single university hospital, while the other received the same treatment spread across multiple hospitals.

Why Long-Term Patients at a Single Hospital Show a Smaller Inquiry Amount

When the covered out-of-pocket payments at a single medical institution reach the annual maximum ceiling of 8.26 million won (as of 2025), the hospital thereafter does not bill the patient but claims directly from the National Health Insurance Service (NHIS). Since hospitals cannot know a patient's income level, they apply the highest threshold to everyone. Money filtered out at the counter in this way was never paid by the patient in the first place, so it is not included in the post-hoc refund inquiry amount.

In contrast, a patient who visited multiple hospitals never reached this threshold at any single one, so all covered out-of-pocket payments were made at the counter. Therefore, the entire portion of the annual total that exceeds the income-based personal maximum appears on the inquiry screen. As a result, the patient who visited multiple hospitals shows a larger amount on the inquiry screen.

However, once refunds are completed, the covered out-of-pocket amounts ultimately borne by the two patients are the same. The patient who was hospitalized at a single hospital effectively received part of their refund in advance by paying less at the counter during the hospitalization.

Steps to Check When the Inquiry Result Differs from Expectations

① Divide receipts by hospital and total the annual covered out-of-pocket payments for each. If any hospital exceeded the threshold, that excess is missing from the inquiry amount.

② Filter out non-covered and selective-benefit amounts. These two categories are excluded from the out-of-pocket maximum calculation from the start.

③ If you received medical cost support from the national or local government, those amounts are also excluded.

④ Outpatient fees and pharmacy dispensing fees are included in the total, so they should be gathered together.

⑤ Any difference that remains unexplained after this process can be verified by requesting the calculation details from the NHIS.

[This article is general information summarizing how the NHIS's out-of-pocket maximum system applies to typical hospitalized patients, based on the NHIS's operating standards. Individual maximum amounts and refund amounts vary depending on income bracket, type of hospitalization, and NHIS calculation results, and a separate maximum applies to long-term patients at long-term care hospitals. As the system may be revised, final confirmation should be made through official NHIS channels. AI assisted in part.]