One in three people are expected not to cooperate with identity card checks, Home Office papers from 2004 suggest.
The Freedom of Information request was made by Mark Oaten in 2004
Papers revealed under information laws show officials have worked on the basis 60% of people who have a card would be expected to carry it with them.
They assume another 10% would confirm their ID via fingerprint or eye scans but 30% "will refuse" to voluntarily show their card or biometric data.
The Home Office said the documents were "incredibly out of date".
A spokesman said the identity card scheme had evolved a great deal since these "historic documents" were produced.
But he declined to say whether the assumptions - which only covers people who have got an ID card - themselves had changed.
The working assumptions were revealed in the documents published by the Department for Work and Pensions under the Freedom of Information laws.
They show that the assumption was that the cards, due to be introduced on a voluntary basis from 2008, would become compulsory to own - though not carry - in 2014.
Lib Dem MP Mark Oaten had asked for the information to be made public when he was the party's home affairs spokesman in 2004.
The department had resisted his request, which came under the Freedom of Information Act.
But the department was ordered to release the data by the Information Commissioner - a decision which was subsequently backed by the Information Tribunal.
'Halving identity fraud'
The assumptions were included in reports about the costs and benefits of the scheme in reducing identity fraud.
In a letter to Mr Oaten, released with the information, the DWP said the information was produced in October 2004, but as government policy about the ID cards had changed the original estimates "are no longer valid".
They do show that at the time the DWP expected ID cards to halve identity fraud from Income Support and Jobseekers Allowance funds from £50m to £25m a year.
The background assumptions reveal officials expected it to take six years for everyone to get an ID card.
Ninety per cent of people would have got them combined with a passport or driving licence - combinations that have since been changed in the current version of the scheme.
Foreign national residency permits would account for about 3% of all identity cards, with 7% being taken by people independently of getting a new passport or driving licence.
The Liberal Democrats and the Conservatives both oppose the identity card scheme.
Liberal Democrat home affairs spokesman Jeremy Browne said: "A major failing of ID cards is that it will cost billions of pounds to coerce law-abiding people into providing their details while those with genuinely malign intentions will strive to avoid complying with the authorities."
Labour says ID cards will have a wide range of benefits and plans, if it wins the next election, to bring in new legislation to make it compulsory to own - but not necessarily carry - a card.