“From the western mountain town of Lares to the capital San Juan, officials are wrestling with how to bring the underground economy out of the shadows and onto the tax rolls without creating such an onerous financial burden that thousands of small and medium businesses can’t survive. More than a quarter of the island’s economy is informal, some studies say, from large companies evading taxes to individuals selling items for cash at roadside stands. But estimates vary widely because the activity can be so hard to track.”
Source: Desperate for taxes, Puerto Rico tries to get grip on underground economy | Reuters