Businesses with empty premises are exploiting a tax break intended for charities to avoid paying full rates, a BBC investigation has found.
High Streets across the UK have their fair share of empty stores and boarded-up properties - some industry experts estimate one in ten units currently stand empty.
Empty or not, the owners or tenants of these properties still have to pay business rates, the same way households pay council tax.
And in these economically hard times, some sections of Britain's business community have been working hard to find ways of not paying the full whack.
"The work we do is only possible because of rent-free space," says Shaylesh Patel, founder of the charity Healthy Planet, which gives away unwanted books which would otherwise be sent to landfill - it does not actually sell anything.
Landlords are keen to bring in charities to take over empty properties, as they present a means of cutting the amount they themselves pay in business rates.
Business rates are paid by the occupier of a property, but charities only pay 20% of what regular businesses pay.
So, to entice charities to use empty premises, landlords are offering to pay rates on a charity's behalf - reducing their own rates bill by 80%.
Some landlords are so keen to get charities in as tenants, they even throw in a donation.
"They give us the space rent-free, and on average they give us half of what they would have paid in business rates," explains Mr Patel.
"Out of that we're able to pay for our rates bill, and the on-going cost of volunteers... and that's how we can fund our activity".
It used to be the case that if a commercial premises became empty the owner was entitled to a rates holiday - they did not have to pay anything for three months, and after that only had to pay 50% of the rates, as long as the property stayed empty.
However, in 2008 the Labour government scrapped the 50% discount for empty shops and a lot of businesses were suddenly hit with a higher tax bill - although discounts remain for businesses in Scotland and Northern Ireland.
Today, landlords still get a three month rates holiday once a property becomes empty, but after that they are liable to pay full business rates which can run into several thousand pounds, hence the motivation to do deals with charities.
"This does seem like it's just a way to avoid paying business rates," says Dan Thompson, of the Empty Shops Network.
"I want to see far more creative and entrepreneurial use in these shops, and allow new businesses to get space... which is far more important."
"There are plenty of alternatives - they could put businesses in there and say 'we won't charge you rent, but you pay the rates'.
Concerns have also been raised questioning whether some of the properties occupied by charities are really servicing any substantial charitable service.
5 live Investigates has discovered that all some charity tenants are doing to qualify for a rates discount is hang posters in the window.
Others operate on an erratic basis - including Healthy Planet, whose Kentish Town store in London is only open in the afternoon on weekdays, from 'midday-ish' on a Saturday, and every other Sunday.
Shaylesh Patel from Healthy Planet says the Kentish Town shop has irregular opening hours because it depends on volunteer staff.
However, Camden Council, which is responsible for collecting rates due on the property, has not granted Healthy Planet any discount on its rates.
Last year Sheffield City Council made a similar decision as it says Healthy Planet was not making full use of the building it occupied.
"These are just two councils out of over 100 that we have been dealing with," says Mr Patel.
"Other councils have given us grants to refurbish our shop fronts, because they want us to be there."
The Charity Commission for England and Wales says it has received a number of queries from local authorities concerned about situations where charities are entering into tenancy agreements on commercial property but where in practice the property is, or appears to be, empty.
The regulator has said it is concerned that charities may find themselves involved in what local authorities might consider to be business rates avoidance by landlords.
It is also concerned that more charities may end up in a similar position to Healthy Planet and be ordered to pay the full rate of business rates if local councils are not satisfied with the nature of the lease agreement.
The Charity Commission is currently investigating three charities - Healthy Planet is not one of them - one of which has over 700 leasing agreements.
"None of this activity would have been necessary if the government had not brought in the changes in 2008," says Jerry Schurder, head of rating with the property consultants Gerald Eve.
Mr Schurder is one of many critics from the business community who believes that forcing landlords to pay full rates on empty properties is unfair.
"Empty property rates is a tax on failure, where businesses have failed, the government wants to rake in some additional revenue.
"The last 50 years are riddled with examples of governments trying to increase revenue by charging empty property rates and they have all been reversed. They haven't lasted at all."
In a statement, Local Government Minister Bob Neill said: "We have doubled small business rate relief helping half a million small firms, and made it easier for small shops and firms to claim tax relief, and given councils new powers to cut business rates for local firms."
However, broader cuts to business rates are unlikely to come anytime soon - especially when cash-strapped local councils are due to profit further from business rates in the near future.
'Overstepping the mark'
"At the moment business rates are collected centrally but in 2013 the money will go to local authorities," explains Bryan Lodge, deputy leader of Sheffield City Council.
Sheffield is one of the councils taking a hard line against businesses it believes are exploiting loopholes to avoid paying rates.
"There was a case involving a company moving boxes of files from property to property, which would be moved after six weeks," says Mr Lodge.
Storing boxes of files enabled the company to declare their property occupied. After six weeks the boxes were removed, leaving the property vacant, and the landlord could claim for another rates holiday.
This is a common ruse, with landlords leasing for short periods of time in order to get three months of rates relief.
However in this particular case the company was set to save even more, as it was using the empty properties for storage.
"If the space is adapted for storage use, then companies can get a six month tax-free period," says Sheffield councillor, Mr Lodge.
"There are opportunities for rate relief, but this appeared to be overstepping the mark."
"We're standing up for the people to make sure rates that are due are paid to the city, and avoid these schemes to get around it."
The Department for Communities and Local Government said it fully appreciates the problems caused by the previous government's reforms and will keep the matter under review.
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