Phasing-in, year-by-year, after conversion
Initially, only new cases, and some existing cases that are linked to new cases, come under the new rules that started on 3rd March. At some time in the future called "conversion day", perhaps during 2004, remaining cases under old rules will be converted to the new rules.
When cases are converted properly (rather than "prematurely converted" via the loophole described and analysed on this web site) they will be "phased-in" if the difference between old rules and new rules results in a large difference in liability. Each year after the start of conversion, a proportion of the converted cases will be governed totally by the new rules, while the rest will only be partly governed by the new rules. After 5 years all cases will be totally governed by the new rules.
Here are estimates of the percentage of old-rules cases that will be totally converted to the new rules at the start of the conversion process and each year after this:
At "conversion day" (perhaps in 2004): 18%
One year after "conversion day" (perhaps in 2005): 51% more (making 69%)
Two years after "conversion day" (perhaps in 2006): 9% more (making 78%)
Three years after "conversion day" (perhaps in 2007): 6% more (making 84%)
Four years after "conversion day" (perhaps in 2008): 5% more (making 89%)
Five years after "conversion day" (perhaps in 2009): 11%; this completes the process.
Parliamentary question providing this information