Use by and best before are not two ways of saying the same thing. One is a safety limit and the other is a quality one, and the law treats them differently. Selling food after its use by date is an offence; selling it after its best before date is not, provided it is still fit and correctly described.
Use by
A safety date, used on highly perishable food such as chilled meat, fish and prepared dishes. After it the food may be unsafe even if it looks and smells fine. Food past its use by date must not be sold or used and should be disposed of.
Best before
A quality date about how long the food is at its best. Food past its best before may legally be sold if it is still fit for consumption and not misleadingly described, which is the basis on which surplus food redistribution operates.
Open dates and secondary shelf life
Once a pack is opened or a dish is prepared, the printed date usually no longer applies and the business sets its own use by date. That decision has to be justifiable, written into the food safety management system and applied consistently, and it is where most date labelling failures at inspection actually happen.
Stock rotation
First in, first out. New stock goes behind old, everything carries a date, and someone checks. FIFO is not paperwork for its own sake: it is what stops the oldest item sitting at the back until it becomes the item that fails.
Questions people ask about use by dates
What is the difference between use by and best before?
Use by is a safety date and food must not be used after it. Best before is a quality date and food may still be safe and legal to sell afterwards.
What does FIFO refer to?
First in, first out: using the oldest stock first, with new deliveries stored behind existing stock so rotation happens by layout rather than by memory.
Who decides the date on food we make ourselves?
The business does, and the decision has to be supportable and recorded in the food safety management system. It is one of the questions an auditor asks about most often.