Putting off decisions until the last minute is costing people nearly £450 a year, it is estimated.
Buying gifts late, not getting around to saving, and planning holidays at the last minute are the most common reasons for wasting cash, according to a survey by Nationwide Building Society.
Nearly two thirds of those questioned described themselves as procrastinators.
A procrastinator is a person who unnecessarily postpones decisions or actions but, as certain things become more expensive closer to the time - airfares, for example - it can be a costly trait.
Men say they waste £571 per year on average versus £325 for women, according to the 2,000 people surveyed.
People were most likely to procrastinate by checking their phones, watching TV and browsing social media, but deadlines and encouragement from others often prompted them to take action.