From 2010, those earning more than £500,000 per year may see their modest pay packet slashed by a tax bill of 43 percent, leaving some of Europe's most vulnerable workers struggling on the bread line.
Real Madrid and Barcelona stars are well known for their frugal lifestyles but this new measure could reduce top footballers' wages to the meager level of a judge or a partner in a law firm.
While the current crop of La Liga stars would be immune to the new law, the Spanish public have reacted with indignation at the idea that the likes of Cristiano Ronaldo may have to cut their monthly hot-pants budget in half.
And the Union of Spanish Nurses and Medical Support Staff has pledged to call a sympathy strike should La Liga's players decide to draw up picket lines.
"I don't know what kind of world we live in when a footballer, who belts a ball around a patch of immaculately cut grass for several hours a month, has to make do with around £1m a year," spokeswoman Gracia Jimenez declared.
"That represents a mere 50 times what we are paid for simply tending to the sick and dying."
The threat of a tax hike has already started to affect players considering a move to Spain.
Ajax striker Luis Suarez, a target for Barcelona, has reportedly started to tighten his belt by selling off his diamond encrusted spare boot bag and laying off forgotten pop star Natalie Imbruglia, who had been hired to sing to him in the bath on Sundays.