A First Aid at Work certificate must be renewed every three years by undertaking a two day requalification course. You can attend a refresher course up to three months before the expiry date of your certificate. If your certificate does expire you have 28 days after expiry to take the course. If your certificate is more than 28 days out of date you will need to complete a three day First Aid at Work course again.
First aiders who hold a valid First Aid at Work certificate are also strongly advised by the Health and Safety Executive (HSE) to undertake annual skills update training to maintain basic skills and to keep up to date with any changes.