Origin

• The phrase "in the red" developed from the use of red ink to mark debt on a financial balance sheet, according to The Phrase Finder. The idiom was first recorded in 1926 in the "Wise-Crack Dictionary."
  
  

Fun Fact

• "In the black" is a less common idiom that refers to being financially solvent. This idiom also derives from the color of ink used on financial balance sheets.
  
  

More Idioms

• Other idioms referencing the color red in the English language include "red tape," which refers to bureaucratic tasks, and "seeing red," which refers to being very angry.