From the available English sources, it looks like there's more to this story. The space is not only used by the church and it's not only used in connection with church activities; one of the possible uses of their space Breccia di Roma advertises on its website is "art exhibitions and small acoustic concerts."
Probably the main issue, though, is that they're using the space as office space for the IFED, which is an evangelical corporation separate from the church, and it is also a "learning hub" for Union School of Theology which offers "European accredited degrees in theological studies" (in support of this, another advertised use of their space is "seminar/lecture space for the training of leaders and church planters"). I would guess that a corporate office or seminary classroom would count as a commercial or educational use, which is why the Italian tax authority is rejecting the classification of the space as a church.
Personally, I'd say if people have trouble distinguishing what you call a church from a commercial space, you're doing it wrong.
I don't know what you read, but it did not take long to find this. In English.
Chiara Lamberti | Fight over property taxes highlights challenges for Protestants in majority-Catholic country
wng.org
But even before they enter the building, visitors can easily see what it’s used for. A bulletin board in the window contains a list of church events: Sunday services, a children’s art workshop, a monthly practical theology class. Just inside the door, roll-up banners include titles from the current sermon series: “Art and the Gospel. A series of eleven sermons on the role of art in the Bible.” On the right, a small bookcase displays Bibles and Christian books.
The main room is furnished with simple, lightweight plastic chairs; a lectern; and a small, easily transportable table. Downstairs, a library containing dozens of volumes provides theology students with ample material and a place to study and collaborate. Pastors and church planters also use it as a training center.
That’s what the tax agency inspectors found when they showed up on Nov. 21, 2019, to check that what had once been a lucrative downtown store had indeed become a place of worship.
They took photos and notes that day, and De Chirico didn’t think they found any problems. But then came a notification that the tax agency wanted the church to continue paying taxes as a place of business—up to almost 8,000 euros ($8,677) a year, a disproportionate amount for a small community with no business activity whatsoever.
The reasoning—according to the inspectors—was that the building did not resemble a “conventional” place of worship. As evidence, they attached to their report photos of some representative worship spaces: San Silvestro Church, the Grand Mosque of Rome, and the Rome Synagogue. All of those are exceedingly ornate edifices, heavy-laden with decoration, altars, and candles. Since Breccia looked nothing like that, the report concluded, it did not deserve its tax-exempt status.
“You can see that they have a Roman Catholic understanding of religious space in mind and have projected it onto ours,” De Chirico said. “It’s not a bureaucratic issue, it’s a religious freedom issue.”
Perhaps it is as the Evangelical Church claims.
As of 2020, the Catholic Church in Italy’s main source of revenue, a provision in Italian tax law called the “8×1000,” or the “eight per thousand,” has dropped to a historic low.
cruxnow.com
ROME – Since the 1980s, the main source of revenue for Italy’s Catholic Church has been what’s called the “8×1000,” or the “eight per thousand,” meaning a share of everyone’s personal income tax the state distributes between itself and a charitable entity of the taxpayer’s choosing.
Under the 8×1000, taxpayers may choose one of several approved charitable entities, both religious and secular, to which funds will be allocated, although they are not required to do so.
Given that roughly 75 percent of Italians are Catholic, of those who do make a choice, roughly 70 percent choose the Catholic Church as the recipient of their funds, which are managed by the Italian Episcopal Conference (CEI).
For those who make no selection, the 8×1000 funds are divided among the various recipients in proportion to the selections that were made, meaning the bulk of those funds benefit the Italian Catholic Church, providing it roughly one billion euro annually, which CEI allocates toward a variety of charitable initiatives as well as administration and overhead.