Torrevieja has one of the highest shares of foreign residents in Spain, and its market is overwhelmingly resale: bungalows, townhouses and apartments inside urbanisations with communal areas. On this type of property two checks make all the difference before signing: that the Land Registry description matches what you are actually buying — enclosed porches, covered solariums or extensions added over the years are often unregistered — and that there are no outstanding debts to the community.
The second feature is the age of part of the housing stock. Many properties were built before the habitation certificate became a standard requirement, so on resale it has to be renewed or obtained afresh before utilities can be transferred into the buyer's name. Where the property comes from an inheritance, there is the added check that the succession was correctly registered at the Land Registry.
On the tax side, the dominant profile is the non-resident owner who visits for part of the year. That concentrates the work on the Modelo 210 and on one very common problem: arriving with several years unfiled. Regularising on your own initiative, before the Agencia Tributaria asks, substantially reduces the surcharges — and it is best done before selling, because a sale brings the property's entire history to the surface.