Claims that householders in England could face £1,000 fines for refusing to let tax inspectors through their doors have been dismissed as "scaremongering".
Officials in Northern Ireland are being given the power to enter homes to value them as part of a rates shake-up being discussed in Parliament.
Conservatives said Ulster was being used as a "testing ground" ahead of the introduction of a similar scheme to replace council tax in England.
Sir Michael Lyons, who is heading a review of council tax for the Government, has said he is "very interested" in the system, where each property is valued individually.
But a spokesman for the Department of Communities and Local Government (DCLG) said it was "wrong" to suggest the new powers were being used as a trial.
Shadow local government secretary Caroline Spelman said: "Northern Ireland is now being used as a testing ground for Gordon Brown's tax inspectors, from the levying of a new house price tax, to the use of invasive Big Brother computer databases, to new aggressive state powers to enter family homes."
The Tories have previously claimed that moving to the new system would force the average bill in England up by more than £400.
The DCLG spokesman said: "This amounts to little more than scaremongering.
"Northern Ireland has a different local government finance system to England - for example, council tax was never introduced there - and different considerations apply."
The Lyons review is due to report to ministers at the end of the year.
