Mortgage interest rates in the Eurozone are on the rise, putting Britons who have borrowed to buy holiday homes in Spain under increasing financial pressure.
As a consequence, many are turning to holiday rentals to help pay the bills.
But after recent scare stories reporting that most holiday rentals in Spain are illegal, and that some Britons have had fines of up to 30,000 Euros slapped on them for renting without a licence, many owners are now having second thoughts.
"When I heard about this I immediately contacted my rental agency in Spain, but it was news to them as well," says buy-to-let investor David Harris, 52, a hotelier from Essex, who rents his 2-bed apartment in Mijas on the Costa del Sol to tourists.
"Property forums are full of contradictory advice, which just leaves you more confused.
" Aileen Hutchinson, 57, a semi-retired health and safety professional from Derbyshire is also concerned.
"We have recently bought a house in Denia on the Costa Blanca, with the intention of renting when we aren't using it to assist in its upkeep," says Hutchinson, whose townhouse is on a development with 18 other properties.
"A disgruntled neighbour has warned us that we need a licence from the Spanish Tourist Board to rent.
With mortgages going up this is serious issue for half a dozen of our neighbours.
" A recent survey at the Spanish property portal Kyero found that 82% of (mainly British) respondents didn't know whether rental licences were required in their area of Spain.
"Clearly, there is a lack of knowledge and awareness about this particular aspect of Spanish law," says Martin Dell, head of Kyero.
The question is further complicated by the distinction, under Spanish law, between 'tourist apartments' (apartamentos turisticos) and 'holiday homes' (viviendas vacacionales).
"The former are a special category of property built and licensed specifically for renting out to tourists, normally in a complex with certain facilities and services under the management of one company, whilst the latter are private residencies rented out by owners to holiday makers on a part time basis," explains Maria de Castro, of Costa Luz Lawyers in Andalusia.
This being Spain, the rules are often ignored, and some developers have been merrily mis-selling 'tourist apartments' as private properties to unsuspecting British buyers who aren't aware of the distinction.
'Tourist apartments' have use restrictions, and need a licence if rules are enforced.
Fines can be incurred if they are rented without satisfying regulations concerning services and facilities.
But most Britons own what Spanish law defines as 'holiday homes', so the question is do you need a licence to rent these out to holiday makers, as you do in other countries like Portugal and Italy? In Spain, with its system of autonomous regional governments, the answer depends upon where your property is.
"You don't need a licence to rent out a private apartment or villa to holiday makers on mainland Spain," argues the owner of one rental management company.
"We have had our specialist lawyers check this for us, and with 3,500 holiday rentals this season we can't afford to make a mistake.
" I cannot confirm that this is correct for all areas of mainland Spain, as regional restrictions do appear to exist.
In Murcia, for example, you need to register with the department of tourism before you can rent a private property to tourists, and can be fined for not doing so.
In Andalusia, on the other hand, you only have to inform the local government of your plans, and in the Valencian region you don't need to do anything, at least according to local lawyers and the regional government.
So it does appear that most British owners of private properties on mainland Spain can relax, though you should always clarify your case with a local lawyer.
The islands, however, are another story.
Powerful hotel lobbies in the Balearics and the Canaries have pushed for local laws that make it difficult or impossible for owners to rent legally to tourists.
"In the Balearics you can only rent official 'tourist apartments' to holiday makers, not private residential apartments," explains Isabel Loeffler of Loeffler Legal Centre in Mallorca.
"The only kind of residential property you can rent out is a detached villa, but only if you have a licence.
" The department of tourism in Palma confirms this, and adds that licences to rent detached properties are no longer being granted in Mallorca (though it appears that they are still being granted in Menorca).
It's a similar story in The Canaries.
"It is illegal to rent a residential apartment to tourists on a weekly basis, and you need a licence to rent a villa, though they are not issuing licences anymore," explains Mario Izquierdo of Lanzarote Lawyers.
A quick search online, however, turns up thousands of private apartments and villas to rent in both regions, many of them belonging to British owners who may have no idea that they risk fines if they are caught.
"The situation is a bit of a mess" admits Kate Mentink, 63, from Edinburgh, who has lived in Mallorca for 27 years, and is now a local councillor and deputy mayor responsible for tourism and international integration in the popular Calvia municipality in the South West of the island.
"My department's understanding is that all short term rentals to friends and family are fine, provided you declare your rental income and pay taxes, but renting to strangers through a tour operator, agency, or even the internet is not allowed without a licence," explains Mentink.
Despite reports of hefty fines for some British owners, it looks like warnings come before fines, at least sometimes.
"Last week we had a case in the town hall of a British man who has been warned for renting out his apartment without a licence.
No further action has been taken, but he could be fined if he continues," says Mentink.
Nobody I have spoken to can confirm that any fines have actually been paid in the Balearics or Canaries, even if they have been issued.
"They might not stand up in court," says one lawyer.
Furthermore, the restrictions only apply to short term tourist rentals, not to longer periods that might suit owners who only use their properties for a few weeks a year.
"Short term rentals are a hassle," says Jan Westwood, of buyer's agency The Property Finders in Mallorca.
"If you use the right kind of contract you can get a winter rental, say from the yachting community, that is much more lucrative and easy on your property, for which you don't need a licence.
" Wherever you own in Spain, but especially on the islands, the best advice is to check with a local lawyer, and bear in mind that you can definitely be fined if you don't declare your rental income and pay tax on it.
You also need appropriate insurance, correct rental contracts for every client, and to check community byelaws if you belong to a community of owners.
Despite the recent alarm about rental licences and related fines, a much bigger problem for British buy-to-let owners in Spain is disappointing rental results.
"Nothing like what I was promised by the estate agent," complains David Harris.
But that's another story.