Under Spanish law all boilers require a compulsory ‘five year' boiler safety check. This is in addition to any regular servicing you may have had carried out. The inspection is carried out by the gas supplier (currently Redexis). The charge is approximately 60€ and the cost is added to your gas bill.
At the time of updating (November 2017) most propoerties are now 10 years old and will require the second of these inspections. If your property is approaching ten years old please check your post-box for a letter from the gas supplier.