WILLIAM BRANGHAM: The Trump administration is starting to turn over personal data to immigration authorities to aid its crackdown on undocumented immigrants living in the country.

The Associated Press reported today the administration is giving ICE access to data of nearly 80 million people enrolled in Medicaid.

And a new report by ProPublica finds the Internal Revenue Service is building a computer program that would give immigration agents unprecedented access to sensitive taxpayer data, including home addresses.

For more on this, we are joined by one of the reporters on that story.

Christopher Bing is technology and national security reporter at ProPublica.

Christopher, thank you so much for being here.

Lay out for us what you discovered.

What kind of data does the IRS have and why does DHS want it?

CHRISTOPHER BING, ProPublica: The IRS is really seen within the government as sort of the Holy Grail when it comes to data.

It has a ton of personal identifiable information for the vast number of Americans and also undocumented people that live in this country.

And that information includes home addresses, familial relations, employment information.

It also includes information about their banking and financial situation.

And so in the hands of immigration enforcement officers, it could really be a treasure trove.

WILLIAM BRANGHAM: For people who might be surprised by this, people who are undocumented in the U.S. are paying taxes and thus their data is with the IRS?

CHRISTOPHER BING: That's exactly right.

Yes, the IRS really encourages everyone in the United States who makes an income to pay taxes.

And that includes undocumented immigrants.

And there's a whole separate category for immigrants to file taxes.

And, historically, the way it's been viewed is that these immigrants would pay taxes, in the hopes that it would help them in immigration court.

It would show their life here, the fact that they're paying taxes, that they're following the law, and they actually viewed it as something that would help them in the immigration process.

They never expected that it would then be used against them in this way.

WILLIAM BRANGHAM: So you saw the blueprints for this particular computer program.

How would it work in practice?

CHRISTOPHER BING: Yes, it's actually -- the system is still in development.

But it is -- the experts that we spoke to said it's quite crude in design and it would basically just ingest a giant spreadsheet created by DHS and by ICE of their targets.

This spreadsheet would need to have a few important pieces of information.

You would have the target's name.

It would need to have at least the last address that ICE has on file.

How complete that address would be is something that I think is still being figured out.

It would need to have the criminal statute that they're being investigated.

And so far, from discussions that we have had with our sources, it's been quite burdensome for ICE to meet this bar.

And that's part of the push and pull that we're seeing internally right now.

WILLIAM BRANGHAM: We know that Melanie Krause, the acting IRS commissioner, resigned because of details about this coming out.

We have seen two other internal IRS officials, chief counsels, have been pushed out as well.

How significant of a change would this program be in terms of IRS policy?

CHRISTOPHER BING: The real number of people that have left as a result of this growing partnership with ICE is close to the hundreds, actually.

There's been dozens of engineers that have left, lawyers, people in the privacy office.

And many of them have left, in part, because they view this as unethical.

But another part of this is that they actually see the legal risk in doing so.

Taxpayer data is among the most protected and strictly regulated in the United States government, and disclosing it to an unauthorized party carries a felony of up to five years.

So there's a lot of people who've left the agency, and that's a little bit unique in the broader Trump administration in terms of the type of pushback that we're seeing.

And they're getting closer to launching the system.

It looks like it could launch by the end of July.

And so the IRS is unique in that, really, culturally, people are taught from day one that you have to be very careful with taxpayer information.

And for them, for many of them, this whole effort kind of breaks that ethos.

WILLIAM BRANGHAM: What has the IRS said in response to your reporting?

CHRISTOPHER BING: The IRS has been fairly quiet.

The Treasury Department has essentially denounced our reporting, as has the White House.

They have said that this is all legal, that this follows with the president's priorities to deport undocumented immigrants.

And they said that there was a court that essentially said this agreement complied with the law.

But that court did not review the blueprint that we have seen, and the court only ruled on the broad contours of the agreement.

WILLIAM BRANGHAM: Your story notes -- I'm going to read a quote from this.

It says that the tax and privacy experts -- quote -- "worry about how such a powerful, yet crude platform could make dangerous mistakes."

What do you mean by that?

What are the risks here?

CHRISTOPHER BING: Yes, the entire way that the IRS searches for individuals in its database is with an identification number.

They have their own identification number, and that's how they can find that the Chris Bing that they're looking for is in fact the Chris Bing that lives in Washington, D.C., that is supposed to pay this amount of taxes per year.

By searching by name, there's an inherent amount of risk there, because there could be multiple people with the same name in a specific county, in a specific zip code, and you have the risk of potentially identifying the wrong person, and eventually, in the wrong situation, potentially having deportation officers show up to that address.

And so the sources that we spoke with were concerned about that type of thing, a mistaken identity, and of innocent people being called up in DHS' dragnet.

WILLIAM BRANGHAM: Christopher Bing, a tremendous piece of reporting for ProPublica.

Thank you so much.

CHRISTOPHER BING: Thank you.