A spent conviction is one that cannot be disclosed or taken into consideration for any purpose. Eligible convictions become spent following a 10 year conviction and proven offence-free period for adults, and a 5 year conviction and proven offence-free period for juveniles.
Does a conviction ever go away?
Although convictions and cautions stay on the Police National Computer until you reach 100 years old (they are not deleted before then), they don't always have to be disclosed. Many people don't know the details of their record and it's important to get this right before disclosing to employers.
How do I know if a conviction is spent or not?
If you're still in your rehabilitation period following a criminal conviction, your conviction is unspent. Any custodial sentence over two and a half years stays unspent. If you were found guilty of a criminal offence by a court, following the specified time-period, your conviction will be considered “spent”.