Nearly half of Britain's workforce has a reading age little better than children leaving primary school, according to a damning report due to be published by MPs.
The report from Commons Public Accounts Committee is due to show that some 16 million adults in the UK hold down regular employment despite having numeracy skills of level one or below, the equivalent of someone aged 11 years-old and younger.
When it comes to literacy, around 12 million people in employment are struggling at the same level, the report has said.
In the report, which is set to be published today, the MPs are also expected to criticise the government's initiatives for tackling the issue, arguing that the billions of pounds that have been put into tackling low numeracy and literacy have achieved little.
The Department for Education and Skills is spending some £6 billion on a programme called Skills for Life scheme by 2010, which was launched in 2001 with the aim of improving the skills of 2.25 million adults.
To achieve level one in literacy a person is expected to "understand straightforward texts of varying length on a variety of topics accurately and independently" and "obtain information of varying length and detail from different sources", according to the DfES.
The MPs are due to focus on poor quality of provision and teaching as a major reason for lack of progress.
Training is also a problem for those in low skilled jobs, the report will say. "Many employers do not place a high priority on staff training and are only likely to become involved if the training offered is flexible," it will argue.
Edward Leigh, the Conservative MP and chairman of the PAC, told The Guardian newspaper: "The low level of literacy and numeracy in the adult population is bad for national productivity and bad for those individuals who may struggle to cope with work and daily living.
"The department has the laudable long-term aim through its 2001 Skills for Life strategy of making sure that England has one of the best literacy and numeracy rates in the world.
"But the task is a huge one and will become increasingly difficult and expensive. The department must harden up its estimates of future costs. It must also zealously hold the line against any dilution of qualification standards," he added.
Skills minister Phil Hope said one of the difficulties the government faced was that it was tackling a "huge legacy" of poor adult literacy and numeracy skills.
"Poor skills may cost the country as much as £10 billion a year and our continuing investment reflects this," he said.
"Already, 3.7 million adults have taken the first step to engaging in learning, with over one million of these going on to achieve first qualifications," he added.