In an article published on 1 February 2016 (see Lee Boyce reported that legal firm Omnia Strategy has taken on landlords' legal fight over mortgage tax relief.

Under the heading 'Cherie Blair steps into landlord mortgage tax relief battle as her legal firm claims Chancellor's move breaches human rights' he wrote:

A legal campaign to fight 'unfair' mortgage tax relief changes for buy-to-let landlords is stepping up a gear today as Cherie Blair MBE QC throws her weight behind the battle.

The changes, likely to hit Britain's army of small-scale landlords hardest, were announced by Chancellor George Osborne in the July Budget.

They will curb the amount of tax that landlords can claim back on their property investments and could mean buying and renting out property is no longer viable for many.

But Mrs Blair's law firm Omnia Strategy has sent a legal letter to the HMRC stating the changes breach landlords' human rights. She believes the campaign has a 'reasonable chance of success.'

Some experts believe rents could rise and tenants could be evicted as a result of the changes, as landlords look to sell before the changes are phased in from April 2017.

According to Treasury forecasts, the tax relief changes will net it almost £1billion a year by 2021. 

The letter from Omnia has been issued on behalf of two landlords – Steve Bolton and Chris Cooper. They started a crowdfunding campaign to fight the changes and managed to raise £50,000 within a week.

The Government must respond to the legal letter by Wednesday 10 February.

A successful challenge to the tax would be embarrassing to George Osborne – and even more so the fact it is being spearheaded by the wife of the former Labour leader and Prime Minister Tony Blair.

Cherie and Tony Blair and their children have a number of properties, worth millions of pounds.

Last year, the Daily Mail reported that they had amassed a £25million property empire snapping up seven houses and 27 apartments across the UK, including a £8million Grade 1-listed 17th century manor near Aylesbury in Buckinghamshire.

A parliamentary petition to scrap the changes, launched in the summer, attracted 60,000 signatures before closing – not enough to start a debate.

Thousands of buy-to-let landlords will see earnings hit as the amount they can claim as relief will be set at the basic rate of tax – currently 20 per cent.

Some current basic-rate taxpayers will also be hit, because the change will push them into the higher-rate tax bracket. It will be phased in over a four-year period from April 2017.

Currently, landlords can claim tax relief on monthly interest repayments at the top level of tax they pay of up to 45 per cent.

Under the new system, section 24 of the Finance Act 2015, they will get a 20 per cent tax credit for mortgage interest.

The Government said in its petition response that 'it is committed to a fair tax system' adding: 'This relief is not available for ordinary homebuyers and not available to those investing in other assets such as shares.'

The Chancellor says he wants to level the playing field between homeowners and buy-to-let investors. It is believed around two million are now landlords and the number renting privately has ballooned in the last decade.

Mr Bolton and Mr Cooper argue the changes overturns a fundamental business principle where income less costs equals profit.

They add that this will result in some landlords who finance their business with mortgages paying tax despite making no profit on their letting business.

The pair say the Government has excluded the most wealthy property landlords, who are able to make cash-only purchases, as well as institutions, corporations and overseas landlords, and those who own commercially let holiday homes, all of whom are unaffected by the change. 

Omnia argues the policy discriminates against individual buy-to-let investors by denying them the same rights as other business owners.

The legal challenge is being made against the new policy on the basis that it breaches the European Convention on Human Rights.

Alongside Cherie Blair, human rights lawyer Adam Smith-Anthony is also working on the case. Steve Bolton said: 'This tax grab is unfair, undemocratic and underhanded, and we believe it is unlawful on a number of points.

'In no other business are costs wholly incurred to fund the business liable for taxation. In addition there is no substantiation in the Government's proposal that the changes will create a level playing field between homeowners and buy-to-let landlords.'

Mr Bolton owns around 20 residential and commercial properties. He is also the founder and owner of Platinum Property Partners, a buy-to-let specialist with a portfolio worth a total of £200million.

Mr Cooper is a part-time landlord who is using buy-to-let as part of his pension.