Pritzer said the decision aligns Illinois' tax day with the federal government's and gives "millions of taxpayers three additional months to file their individual returns."
Tax preparers were among those who had been pushing for that three month postponement, which the governor said will not impact greatly the processing of tax refunds.
"Refunds will continue to be distributed in a timely fashion," the governor said.
Along with the reprieve for taxpayers, the Pritzker administration also announced that it was making hundreds of millions of dollars in loans and grants available to small businesses and restaurants hit hard by mandatory shutdowns.
Businesses can apply to the programs on the state's Department of Commerce and Economic Opportunity website.
The measures come as the number of COVID-19 cases in the state nears 2,000.
The Illinois Department of Public Health announced 330 new COVID-19 cases Wednesday, with three additional deaths.
A Kane County man in his 90s, a Cook County man in his 60s and a Will County woman in her 50s died after being diagnosed with the virus, the IDPH said.
There are now three new Illinois counties reporting COVID-19 cases -- Douglas, Marshall and Morgan. Patients range in age from younger than 1 to 99.
Coronavirus Illinois Update: Latest news on 1,865 COVID-19 cases, Chicago area impact
Of the 330 new cases, Illinois health officials said two correctional officers and an inmate at Stateville Correctional Center in Lockport Township have tested positive for COVID-19.
The correctional officers are recovering at home, while the individual who is incarcerated is being isolated in the hospital, state health officials said.
The facility is on a 14-day lockdown, while those who were identified as having possible exposure are being quarantined, according to the IDPH.
A contractual worker at Sheridan Correctional Center in LaSalle County has also tested positive for coronavirus.
That facility is also under lockdown for two weeks.
According to the Cook County Sheriff's Office, four members of the correctional staff and one sheriff's police officer have tested positive for COVID-19.
Seventeen detainees at the Cook County Jail have tested positive, and 31 others are awaiting results.
Illinois officials also addressed plans to pour money into banks on Wednesday.
"In turn, they've agreed to turn around and use the money to help small businesses and nonprofits pay rent, purchase supplies, and to make payroll," said Illinois Treasurer Michael Frerichs.
The state is also directing money to the hotel industry that's now bracing for a wave of layoffs as occupancy rates fall into the single digits.
Several hotels have partnered with the state, providing some 20,000 rooms for health care workers, first responders and hospital overflow.
"Our hoteliers throughout the state of Illinois have stepped up and answered the call of duty in a time of crisis to open their doors to some of the most vulnerable and at-risk citizens in our state," said Michael Jacobson of the Illinois Lodging and Hotel Association.
Regarding the efforts in Washington to pass a stimulus bill, the governor could not say how much he expects Illinois to receive. But he said his team will work to collect every dollar that the state is owed.
With the number of cases continuing to climb and fear and hardship growing, the state's top health official grew emotional.
"It is hard. I'm a doctor. I'm a mother, and I just buried my father last month, and so when I think about people who can't do what I did for my father last month, I feel it very real as to what people are going through and the sacrifices that they're making," said IDPH Director Dr. Ngozi Ezike.
The rise in cases comes amid an outbreak at a long-term care facility in southwest suburban Willowbrook.
The DuPage County Health Department reported yet another infected staff member at the Chateau Nursing and Rehabilitation Center just a day after the first resident passed away from the virus.
A total of at least 46 people connected to the facility have confirmed to be infected, including 33 patients and 13 staff.
The nursing home posted a letter on its website, saying "Life here at our home is slowly returning to normal."
"There is probably a 'new normal,' but things are moving and getting better each day," the facility said.
From the start, representatives for Chateau have said the sick, but not hospitalized, are being kept in isolation, and all staff is having their temperature checked at the start of their shifts.
In an effort to prevent any further spread, residents are also having their vital signs checked more often, those who are ill even more so. As with all other nursing homes all non-essential visitors are banned from entering the building.
Dr. Ezike addressed continued efforts to limit contagion at all nursing homes across the state.
"We have provided extensive guidance and are working tirelessly with nursing home facilities on infection control practices, individual and group monitoring, isolation and quarantine and health and medical care," Dr. Ezike said. "But we will see cases continue to grow."
A 93-year-old resident of Three Crowns Park in Evanston also died of complications from the coronavirus at a nearby hospital. He was one of at least two infected residents.
"Personally, I am very concerned because I am one of the most vulnerable people," Steve Warner, a resident at the facility, told ABC7 last week.
Relatives of Three Crowns Park residents said the facility is now on lockdown.
Tonya Davis said she is a certified nurse's assistant and was terminated by Chateau for speaking out.
"They have negatives in the room with positive people," Davis said.
Chateau has not responded to requests for comment. DuPage County said they do not have anyone on-site for day-to-day operations, but stressed that everyone who is sick is in isolation and the county is in touch with the care facility every day.
With the number of cases statewide continuing to rise, officials say more than half the state's hospital beds are now occupied.
Pritzker said shuttered hospitals, like Metro South Hospital in south suburban Blue Island, may be reopened.
The state is also calling on existing hospitals to expand. Rush University Medical Center has already turned a lobby space into an area for treatment.
"We have expanded our emergency department," said Dr. Omar Lateef, Rush Medical Center CEO. "We have transformed entire units into COVID hospitals with many units that are designed to take care of patients."
State officials are also looking into using hotels as quarantine centers, something Mayor Lori Lightfoot announced Chicago will be doing in her Monday press conference.
"In two weeks we would need over 28,000 additional non-ICU beds and over 9400 additional ICU beds; that's untenable," Pritzker said.
Another issue is staffing. Over the weekend, Pritzker made a plea to retired health care workers, asking them to help with the influx of patients. The governor said 180 people applied in the first 24 hours.
While the state works to prepare the healthcare system, Pritzker said his "stay-at-home" order, earlier closure of schools, bars and restaurants are helping stave off a tsunami of patients.
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When asked if he'd extend the "stay-at-home" order past April 7, he responded, "I'm trying to follow the science here, and I am concerned that we may have to extend that deadline."
"The question that everyone wants answered right now is how long is all of this going to last," Pritzker said. "The honest answer is we don't yet know."
Pritzker added that he disagreed with talk from President Donald Trump and others about lifting national guidelines that are keeping people from work.
"I don't think he's listening to the science," Pritzker said. "I think he is operating, you know, he's looking at the stock market, which I know he essentially judges himself by."
Coronavirus: From hand-washing to wearing masks, here's how to protect yourself
Weeks into the battle against coronavirus, state leaders say the federal government has filled just a fraction of Illinois' requests for masks, gloves and other PPE.
Pritzker stated that until this week they only received one shipment of supplies they requested back on March 6, three days before the state's disaster proclamation. He said the initial shipment of 123,000 N95 masks was only 10% of the 1.2 million they requested.
Illinois has been left to acquire that critical gear on its own for their first responders and medical professionals.
Those who would like to help by donating PPE should contact PPE.Donations@Illinois.gov.
The Illinois Department of Public Health has created a hotline at 1-800-889-3931. More information can be found at the IDPH website and the Chicago Department of Public Health website.