My insurance company called to say I have a pending fine

When DGT or other issuing authorities can't reach the car owner at their registered address, the fines are notified through the TEU, an online platform at the Official State Gazette or BOE. The TEU service is not available in English, but some insurance companies check it daily in case their clients appear in the public announcements. If that is the case you will receive a call and they will provide basic information about the fine. The most important information you must request is:

1. Reference number: this number is mandatory to pay for the fine or to gather further information. DGT reference numbers, por example, have 12 digits. 
2. Date of the offence: the date is useful to pay for the fine. 
3. Amount to pay: the total amount can be reduced up to a 50% in the early payment window (20 days after the notification). 
4. Issuing authority: you will have to contact them for full details. 

Fines get published at the TEU when the recipient of the letter cannot collect it at the post office or when the address is not updated. In Spain DGT uses their own database to send fines, and to complicate things further they have two databases, the Driver Registry and the Car Registry, so if you buy a new car and provide an updated address, they do not update the driver's address!!! It sounds crazy, but you need to request that the address be updated for notification purposes if you don't want to get a call from your insurance company. 

If you have been living in Spain long enough and your land line number remains the same, you are likely to get a call from a company that will offer disputing the fine for about 40 euro. Do not hire their service, for they will send an automated writing that has no effect and you will have to pay the fine in full afterwards.