'Impenetrable' council tax benefit rules backed by AMs
New council tax benefit rules in Wales criticised as "completely impenetrable" and impossible to implement correctly have been backed by assembly members.
A cross-party committee said they were so complex, specialist lawyers could not work out the policy intentions.
The vote was needed so 330,000 of Wales' poorest households can receive full or partial rebates from April.
The Welsh government said its offer of technical briefings had been ignored and the level of details was necessary.
Ministers said this was because of the vast range of household circumstances which had to be taken into account.
The committee members said they had been left particularly baffled by references to a volcanic eruption in Montserrat, an island in the West Indies, in the 1990s.
They said it was "anybody's guess" what relevance this had to council tax in Wales in 2013.
In their report to AMs, the constitutional and legislative affairs committee said: "The regulations, as a whole, are completely impenetrable.
"Even to lawyers with an extensive background in statutory interpretation, it is impossible to fathom the policy intentions from the regulations.
"Local authority officials charged with implementing them will find it completely impossible to be certain that they are implementing the regulations correctly.
"It will be even worse for members of the public - and those such as CABs (Citizens Advice Bureau) who advise them - who seek to ensure that they are being granted the benefits to which they are entitled under the schemes. This is due to the complexity of every part of the regulations."
The committee, chaired by deputy presiding officer David Melding AM, said in some cases those trying to interpret the regulations were left on a "ridiculous hunt" for simple definitions.
They added: "Quite what relevance 'a person in Great Britain who left the territory of Montserrat after 1 November 1995 because of the effect on that territory of a volcanic eruption' has to council tax in Wales in 2013 is anyone's guess.
"The Welsh government has, quite rightly, advocated accessible legislation. These regulations show how not to achieve that."
But, during the debate on the rules, Mr Melding said it was now in the public interest to pass the regulations to avoid disrupting key benefits.
Earlier, local government minister Lesley Griffiths said she was "disappointed" by many aspects of the committee's report.
She said: "It is disappointing that the committee was unable to take up my offers of technical briefing to assist in the scrutiny process, particularly in light of the comments regarding the impenetrability of the regulations.
"The establishment of the Council Tax Reduction Scheme has involved our replacing a complex, means-tested system which had been developed over a period of 20 years by the Department for Work and Pensions.
"The detail in the regulations necessarily reflects the vast range of household circumstances which must be taken into account in delivering any means-tested system."
The references to Montserrat, for example, were necessary to define exactly who was eligible for support and in what circumstances.
The Welsh Local Government Association (WLGA) said the regulations reflected the fact that operating such schemes was a "complex business".
It said in a statement: "The regulations, although complex, seek to replicate those previously put in place by the UK government, to protect existing entitlements for Welsh benefit claimants in 2014-15 as far as possible.
"Local authority benefits managers have been working with the Welsh government to improve the regulations and will have to implement them on the ground.
"As long as practitioners don't find them impenetrable, then that is half the battle."
Responsibility for delivering council tax benefit in Wales was devolved from last April.
The rules were at the centre of a political row which saw AMs being summoned back from their Christmas break last year for a vote.