not worth the paper it's written on

Meaning

1. not worth the paper it's written / printed on

   having no value, especially legally, or because one of the people involved has no intention of doing what they said they would

From the same entry

• for all is worth
• for what it's worth
• not worth the candle
• worth your salt
• worth your weight in gold
• worth while
• a bird in the hand is worth two in the bush
• more than your job's worth
• put in your two cents' worth
• get your money's worth