Before the changes
The benefits system has always had provision for 'sanctions' where people failed to do certain undertakings as a condition of getting a benefit.
After the changes
There is now much more conditionality attached to getting your benefit. Hence you may find your benefit being withheld or reduced. This change began in 2013.
You may be able to challenge a sanction decision on Jobseeker's Allowance or be entitled to 'hardship payments' during the period of the sanction. If your Employment and Support Allowance has been stopped (or reduced) you may be able to challenge the decision and/or claim a 'hardship payment'. If you pay rent and/or council tax you should make sure that you still claim Housing Benefit/Council Tax Reduction during any period you are told you are not entitled to benefit due to a sanction.
What you can do
Contact the Benefits Helpline for more information about this change and advice on what your options are if you are affected.