 A successful proposal could alter this original value of £10,000 to £9,000 from 1 April 2005 to 31 March 2006, but the second entry from 1 April 2006 would remain unchanged at £12,000.The Local Government Finance Act 1988 gives broad authorisation for regulations to be made about alterations, which can include alterations by the Valuation Office Agency to maintain the list accurately, or proposals by interested parties to change the list.The regulations have differed widely, changing the time-frame of when alterations are effective.