This week's activation of the ContactPoint children directory has provoked an outcry among opponents of the "database state". As does almost every announcement about the National Identity Register and NHS National Programme for IT.

However, the database that underpins current plans for transformational government, in which different agencies routinely share data about individuals, has almost no brand recognition outside Whitehall.

Step forward the Customer Information System (CIS), the central repository of basic data on some 80 million individuals, alive and dead. The CIS was conceived in the 1990s as part of an upgrade of mainframe computer systems handling national insurance and social security systems – the "customer" in question generally has no choice in the matter. The exercise involved a massive clean-up of national insurance numbers, by which individuals are indexed in the system. At the time, the main driver was to cut the politically unacceptably high level of benefit fraud.

The CIS initially went live in 2006, at a cost of £88m. It is already used by HMRC, local authorities, the DVLA and the Legal Services Commission (to check entitlement to legal aid). Under the current transformation programme, it is to become the basic population register of the entire public sector, including the Identity and Passport Service.

Like most of the government's other big systems, the CIS is run by a private sector contractor, in this case Electronic Data Systems (EDS). Like other big systems, it has had its share of delays: the Department for Work and Pensions minister Jonathan Shaw revealed to parliament recently that the project's original completion date of December 2007 had slipped by a year to minimise the risks of migrating data.

Regardless of what happens to ContactPoint or the ID card, the CIS's role seems set to grow. For example, the database underpins the "tell us once" service being tested by local authorities, which allows individuals to notify officialdom of births and deaths only once.

None of this information is secret, but the DWP – even in its new role as "department for the citizen" – does not go out of its way to broadcast its internal workings. Most information about the status of the system and the accuracy of its database is extracted painfully slowly by parliamentary questions and ploughing through specialist reports.

This has to change. As a supporter of the welfare state and an enthusiast for e-government, I see nothing wrong with a core database used across the public sector to prove entitlement (which is not the same as proving identity). I do not think the welfare state can maintain public credibility without such a system.

However the system needs public credibility, too. By definition, an unknown system cannot have that. In a democracy, any national database, particularly one as pivotal as the CIS, must be run in the spotlight of public scrutiny.

For a start, citizens should be encouraged to check whether their personal details are accurate and up to date, not treated as troublemakers when they ask.

Further up the complexity scale, the government should welcome debate on the emerging public sector IT infrastructure and the CIS's role within it. In this context, plans for information-sharing gateways should be open to individual public consultation, not "fast-tracked" through parliament as proposed in the current coroners and justice bill.

As ministers so often say, if you have nothing to hide you should have nothing to fear.