Councils have been asked to review their adoption practices following concerns prospective parents looking to adopt are being wrongly turned away.
It comes after a drop in the number of assessments recommending adoption as the best option for vulnerable children, the Department for Education (DfE) said.
Education Secretary Gavin Williamson made the request and said local authorities should not "shy away" from putting children who are in care forward for adoption.
The DfE has now published updated advice for councils to "make clear" that age, income, sexual orientation and marital status should not be used as reasons to turn away potential adopters.
It added there had been concerns that parents who want to adopt are being turned away despite the law stating they are eligible.
Children and families minister Michelle Donelan said there were "misconceptions" about who can and cannot adopt, which she felt could be putting off potential adopters.
She said in a statement: "Neither age, ethnicity nor sexual orientation should be a barrier to adopting. What matters is the love and protection a parent can provide.
"That is why I have written to councils asking them to make sure they are following the law correctly so that no-one is wrongly excluded."
The new advice follows a further £45m government investment in the Adoption Support Fund which will be available next year, according to the DfE.
More than £1m will also be provided for regional adoption agencies to run recruitment campaigns this year, aimed at finding adoptive families for Bame children, the DfE added.
Adoption UK's chief executive Sue Armstrong-Brown said: "Adoption is a critical route out of care for children who can't return to their birth families and I welcome the government's renewed commitment to ensuring the adoption sector is fit for purpose."
Meanwhile Dr Carol Homden, chief executive officer of children's charity Coram, said: "At Coram, we are really concerned about the drop in number of adoptions and that approved adopters are now outnumbered by children awaiting adoption."
She added: "There are currently over 4,000 children awaiting adoption in this country."
A Local Government Association spokesman said: "Additional funding for regional adoption agencies to recruit prospective adopters is good news, as is the extension of the Adoption Support Fund which has helped so many families.
"We urge the government to also consider investing in the recruitment and support of foster carers to make sure that we have the most suitable placements available for all children."