This is a copy extract direct from the HMRC website:

Spotlights

Introduction

'Spotlights' is all about tax avoidance.
It has a 'consumer protection' role in helping you to avoid unwittingly entering into arrangements that HM Revenue & Customs (HMRC) are likely to see as tax avoidance. It does this by identifying the types of arrangements or scheme which HMRC are likely to challenge. HMRC will do this both by providing you with some help to understand how they distinguish between artificial avoidance schemes and ordinary sensible tax planning and by describing specific schemes. Where HMRC think there may be particular drawbacks to a scheme that might not otherwise be obvious, including the fact that other taxpayers are no longer pursuing their arguments on an avoidance scheme, HMRC will tell you.
In Spotlights HMRC will:

Provide some advice on tax planning to be wary of, listing some indicators that HMRC see as suggesting that a scheme may involve tax avoidance and which it is likely to investigate.
Identify specific schemes which, in HMRC's view, are not likely to deliver the tax savings advertised. Where HMRC see such schemes being used, subject to the particular facts, they will make a challenge and seek to ensure full payment of the right tax with the right due date.

Set out below are a number of indicators of tax planning to be wary of. The inclusion of one of these features does not necessarily mean that tax avoidance is involved, but the more of these features that are present, the more likely it is that HMRC would see the arrangements as tax avoidance and challenge your Self Assessment. If you have doubts about a scheme then you should check with a reputable tax adviser.

Tax planning to be wary of

It sounds too good to be true.
Artificial or contrived arrangements are involved.
It seems very complex given what you want to do.
There are guaranteed returns with apparently no risk.
There are secrecy or confidentiality agreements.
Upfront fees are payable or the arrangement is on a no win/no fee basis.
The scheme is said to be vetted by a top lawyer or accountant but no details of their opinion are provided.
The scheme is said to be approved by HMRC (it does not follow that this is true).
Taxation of income is delayed or tax deductions accelerated.
Tax benefits are disproportionate to the commercial activity.
Offshore companies or trusts are involved for no sound commercial reason.
A tax haven or banking secrecy country is involved without any sound commercial reason.
Tax exempt entities, such as pension funds, are involved inappropriately.
It contains exit arrangements designed to sidestep tax consequences.
It involves money going in a circle back to where it started.
Low risk loans to be paid off by future earnings are involved.
The scheme promoter lends the funding needed.
There is a requirement to take out insurance against the failure of the tax planning to deliver the tax benefits.

Particular schemes

The schemes featured in Spotlights are generally those which HMRC consider have the widest implications and about which there is the greatest need to warn potential users. They will often be schemes that have been disclosed to HMRC and have been given a Scheme Reference Number (SRN). Please note that the issue of a SRN does not mean either that HMRC 'approves' the scheme or that HMRC accept that the scheme achieves its intended tax advantage. These articles are limited exceptions to the usual rule that HMRC do not comment on tax avoidance. No further comment will be made. Only a minority of schemes will appear in Spotlights. In particular, HMRC will not include schemes aimed at very specialised areas, with a limited scope or where HMRC estimate not much tax loss is involved. A scheme that has not featured in Spotlights may still be challenged. You may wish to consider it in the light of the advice above on 'tax planning to be wary of' and consult a reputable tax adviser.

Spotlight 11: Avoiding income tax on pay (3 March 2011)

We are aware that people who have used employee benefit trusts (EBTs) etc to avoid tax on employment income are being targeted with products designed to shelter funds in current schemes from the effect of planned legislation. These arrangements rely on the availability of credit for loan repayments made before 6 April 2012. In HMRC's view while these convoluted arrangements seek to weave a way through the legal changes they do not succeed. Even if they did HMRC would still challenge them as delivering remuneration which should have been subject to PAYE from first principles.
Subject to parliamentary approval, the new legislation will be effective from 6 April 2011 and some aspects of the proposed new law will apply from 9 December 2010. These changes are designed to prevent the avoidance of PAYE and national insurance contributions on employment income.
Individuals considering entering into such income tax avoidance arrangements should be aware that HMRC will pursue people who seek to avoid tax on monies they earn, through the courts where necessary.
Spotlight 10: Stamp Duty Land Tax avoidance (7 June 2010)
Spotlight 9: Gift Aid with no real gift (29 March 2010)
Spotlight 8: Investments to obtain trade loss reliefs ('sideways loss relief') (8 February 2010)
Spotlight 7: Avoidance using Gift Aid (6 January 2010)
Spotlight 6: Employer-Financed Retirement Benefits Scheme (EFRBS)
Spotlight 5: Using trusts and similar entities to reward employees - PAYE and NICs, Corporation Tax and Inheritance Tax
Spotlight 4: Contrived employment liabilities and losses
Spotlight 3: Pensions schemes artificial surplus
Spotlight 2: VAT artificial leasing
Spotlight 1: Goodwill - companies acquiring businesses carried on prior to 1 April 2002 by a related party

Highlights

Where HMRC come across tax avoidance schemes they actively challenge them, through the courts where appropriate.
There are occasions when taxpayers concede that the avoidance doesn't work rather than taking their case to litigation. This section highlights areas of avoidance where taxpayers have conceded that the tax they have sought to avoid is due.
Taxpayers have been conceding the disputed tax in the following avoidance arrangements:

goodwill - companies acquiring pre 2002 business from a related party (Spotlight 1)
artificial leasing (Spotlight 2)
schemes to obtain trade loss reliefs ('sideways loss relief') (Spotlight 8)
abusive off-shoring of financial structures leading to consumption of services by EU customers
VAT avoidance on promotional vouchers issued with sales of services or goods

Contact us

Tax agents can provide us with information about people or companies who may be promoting the type of arrangements covered by Spotlights by emailing Tax avoidance information.
Anyone offered a tax, duty, National Insurance or VAT product they are concerned about can also provide details of the tax arrangement to Tax avoidance information.
Please provide sufficient detail for us to understand the arrangements being offered. If you are willing to be contacted in the event that we need more information please let us know how and when it is best to contact you.