New measures came into effect on 1 January 2011 to strengthen and improve the Disclosure of Tax Avoidance Schemes (DOTAS) rules.

In summary: 

The provisions are contained in  Schedule 17 of Finance Act 2010.

New regulations also:

Finance Bill 2011
From 5 April 2011, transfers of property into a trust will be disclosable under the DOTAS regime. The usual hallmarks will not apply but "grandfathering provisions" will try to ensure that certain transfers will not require repeat notification. HMRC will be providing further guidance.  

Links:

Our overview of DOTAS

HMRC news 

Draft legislation Finance Bill 2011