Wear and tear could force taxpayers to replace identity cards much earlier than ministers have predicted, according to consultants KPMG.
In a report in today's Financial Times researchers urge ministers to revise their estimates that the cards would last a decade.
"Given the inconclusive evidence for the lifespan of the cards we recommend that an increase in damage rates for the cards in the latter stages of the first 10 years should be reflected in the outline business case model or an estimate of cost for a warranty of the card be included," the KPMG document states.
The KPMG report concluded that the government's finances are "robust and appropriate for this stage of development".
Home Office minister Andy Burnham denied the KPMG claims on durability, claiming that there is " general agreement" among card manufacturers that a 10-year lifespan is possible.
The Home Office has maintained that the process of enrolling people on the National Identity register, not issuing the plastic cards, accounts for much of the expense of the scheme.
The department argues that the register will have to be set up to issue biometric passports, and that a lot of the cost is unavoidable and unrelated to ID cards.
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