Under the Regulatory Reform (Fire Safety) Order 2005, there is no definitive answer and it all depends on the type of building/premises you occupy, construction of the building, who carried out the last fire risk assessment (e.g. their competence/qualifications), whether there have been any significant changes since the last fire assessment among many more factors.
The single purpose of a fire risk assessment is to identify any risks within your building and then aim to reduce, remove or eliminate that risk to acceptable levels. It is then your responsibility to carry out the findings of a fire risk assessment which you will find in the action plan and keep on top of the maintenance of your fire protection systems such as the fire alarm and emergency lighting systems by completing your fire logbook on a regular basis.
For most buildings, we would recommend that a competent person reviews your fire risk assessment at least every twelve months as a minimum to ensure any shortcomings are identified and put right on a regular basis and there may have been other changes to your building (for example a multi occupied building), that you are not aware of that could have an impact on the fire safety within your building.
For lower risk properties, you may decide to review your fire risk assessment only every two-three years, this may include a small shop with low numbers of staff and customers or a single storey ground floor office with more than one fire exit. If in doubt, I would recommend you ask a professional fire risk assessor or qualified fire safety consultancy.
Your local Fire Service acts as the enforcing authority for your building/premises and can decide to visit you at any time to check on the fire precautions within your building. They can request to see your fire risk assessment at any time under the Regulatory (Reform) Fire Safety Order 2005 and this is why it is important to make sure your assessment is valid by ensuring it contains up to date information and ensure you are complying with the recommendations within the action plan.
By having it reviewed every twelve months and keeping a fire logbook with all your record keeping, you stand the best chance of complying with fire safety legislation and keeping the occupants in your premises safe. Keeping a daily or weekly checklist is another good idea as these are a good reminder to make sure your fire escape routes are kept clear, fire exits unlocked etc.