Texas hospitals have spent months preparing for the change and have sought to reassure patients that it won't affect their level of care.
Under the executive order announced by Abbott in August, hospitals must ask patients if they are citizens in the United States and whether they are lawfully present in the country.
Patients have the right to withhold the information and hospital workers must tell them their responses will not affect their care, as required by federal law.
Hospitals are not required to begin submitting reports to the state until March. An early draft of a spreadsheet made by state health officials to track data does not include fields to submit patient names or personal information.
Providers will fill out a breakdown of visits by inpatient and emergency care patients and document whether they are lawfully present in the country, citizens, or not lawfully present in the US.
The reports will also add up costs for those covered by Medicaid or the Children's Health Insurance Program, known as CHIP and the cost for patients without it.
"Texans should not have to shoulder the burden of financially supporting medical care for illegal immigrants," Abbott said when he announced the policy.
Florida enacted a similar law last year. Health care advocates contend the law has made immigrants who need of emergency medical care fearful and led to fewer people seeking help, even from facilities not subject to the law.
Florida's early data is -- by the state's own admission -- limited. The data is self-reported. Anyone can decline to answer, an option chosen by nearly 8 percent of people admitted to the hospital and about 7 percent of people who went to the emergency room from June to December 2023, according to Florida's state report. Fewer than 1 percent of people who went to the emergency room or were admitted to the hospital reported being in the US "illegally."
Immigrant and health care advocates have sought to educate the Texas public about their rights. In Florida, groups used text messages, posters, and emails to get the word out. But advocates there have said they didn't see fears subside for about a year.
Health care providers received directives from the state and guidance from the Texas Hospital Association.