Once again, the majority of the nation's hospitals are being penalized by Medicare for having patients frequently return within a month of discharge - this time losing a combined $420 million, government records show.

In the fourth year of federal readmission penalties, 2,592 hospitals will receive lower payments for every Medicare patient who stays in the hospital - readmitted or not - starting in October. The Hospital Readmissions Reduction Program, created by the Affordable Care Act, was designed to make hospitals pay closer attention to what happens to patients after they are discharged.

Since the fines began, national readmission rates have dropped, but roughly one of every five Medicare patients sent to the hospital ends up returning within a month.

In Pennsylvania, 74 percent of hospitals were fined, and in New Jersey, 97 percent were, according to the analysis. The average Medicare payment reduction was 0.73 percent in New Jersey and 0.61 percent in Pennsylvania.

The highest penalty in Philadelphia was 2.5 percent at Pennsylvania Hospital, an improvement over the 3.0 percent it notched last year. The next-highest was Thomas Jefferson University Hospital at 1.9 percent, down from 2.25 percent.

Some hospitals view the punishments as unfair because they can lose money even if they had fewer readmissions than in previous years. All but 209 of the hospitals penalized in this round were also punished last year, a Kaiser Health News analysis of the records found.

The fines are based on readmissions between July 2011 and June 2014, and include Medicare patients who were originally hospitalized for one of five conditions: heart attack, heart failure, pneumonia, chronic lung problems, or elective hip or knee replacements. For each hospital, Medicare determined what it thought the appropriate number of readmissions should be based on the mix of patients and how the hospital industry performed overall. If the number of readmissions was above that projection, Medicare fined the hospital.

The fines will be applied to Medicare payments when the federal fiscal year begins in October. In this round, the average Medicare payment reduction is 0.61 percent per patient stay, but 38 hospitals will receive the maximum cut of 3 percent, a Kaiser Health News analysis shows. A total of 506 hospitals, including those facing the maximum penalty, will lose 1 percent or more of their Medicare payments.

Overall, Medicare's punishments are slightly less severe than they were last year, both in the amount of the average fine and the number of hospitals penalized. Still, they will be assessed on hospitals in every state except Maryland, which is exempt from these penalties because it has a special payment arrangement with Medicare.

These lower payments will affect three-quarters of hospitals or more in Alabama, Connecticut, Florida, Massachusetts, New Jersey, New York, Rhode Island, South Carolina, Virginia, and the District of Columbia. Kaiser Health News found that fewer than a quarter of hospitals face punishments in Idaho, Iowa, Kansas, Montana, Nebraska, North Dakota, and South Dakota.

Most of the 2,232 hospitals spared penalties this year were excused not because Medicare found readmissions to be sufficiently infrequent, but because they were automatically exempted from being evaluated - either because they specialized in certain types of patients, such as veterans or children, because they were specially designated "critical access" hospitals, or because they had too few cases for Medicare to accurately assess.

The readmission penalties are not the only fines hospitals face this year. As it did last year, Medicare is also giving out bonuses and penalties based on a variety of quality measures. The government has not yet announced those, but they also begin in October. Those financial incentives will total about $1.5 billon. Medicare will also punish hospitals with high rates of infections and other avoidable occurrences of patient harm.

Hospitals have been lobbying both Medicare and Congress to take into account the socio-economic background of patients when assessing readmission penalties. They argue that some factors for readmissions, such as whether patients can afford medications or healthy food, are beyond their control.

The Medicare Payment Advisory Commission, which advises Congress, has recommended altering the readmission penalties. The National Quality Forum, a nonprofit that Medicare looks to when creating quality metrics, is examining whether socio-economic factors should be included when calculating readmission measurements, as well as other barometers of hospital quality. But that experiment will take two years to complete.