The first set of provisions from the Care Act 2014 have now come into force so that all carers can now get assessments for their needs and support.
Before the changes assessments were only for those providing regular and substantial care and there was no obligation for local authorities to meet carers needs.
Figures from Carers UK showed there are 5.4m carers in England, while nearly 2m people take on caring responsibilities annually.
Of carers giving full-time care, 80% have suffered ill health and nearly 2m giving up work to care for older or disabled relatives.
The Care Act's cap (the Dilnot Cap) on the costs of care will be implemented from 2016.
Heléna Herklots, chief executive of Carers UK, said: "They are an essential first step in improving support for carers; now we need to see the resources put behind them.
"We are providing expert advice on the new rights for carers and for professionals who will be implementing them.
"We'd urge all families caring for a disabled, frail or ill family member or friend to find out about their new rights to an assessment from their local authority.
"Many carers say that they find the assessment process helpful in understanding what support might be out there and helping them to make decisions."
David Pearson, president of the Association of Directors of Adult Social Services, said: "We have still not fully agreed with central government the additional costs that we shall have to incur in order to implement the legislation fully and successfully.
"There is no doubt that part of that success would lie in ensuring that the £4.3bn gap in funding between now and 2020 is addressed. There is a mismatch between rising demand and reducing resources.
"But ongoing discussions about these issues should not detract from the importance of the 2014 Act, the significant changes it will wrought in our services, and the important benefits it will bring older people and adults with disabilities in the coming years and decades."