Back dated Inheritance Tax threshold

[DonKiddick]

I have read that the recent changes to IHT take effect immediately and also are back dated indefinitely. Does this mean that when a husband dies and everything passes to his wife she then has an IHT threshold equivalent to her own allowance plus the allowance that her husband had at the time of his death?
For example if the husband died in 1991 (when the threshold was �140k) is the amount that the wife can now leave free of IHT a total of �440k (her own �300 plus her late husband's �140k)?
What if the husband died in 1991 and the wife in 1996?
The wife's threshold was then �200k. The combined threshold at that time would have been �340k. Is it possible now to reclaim any IHT paid on the wife's estate between �200k and �340k?

[dzug]

Not quite.

If the husband dies in 1991 and the wife in 1996 there is no backdating. The second death has to be on or after 9 October 2007 for backdating to occur.

If the husband died in 1991 and the wife dies now, what she gets depends on how much of the husband's allowance was used in 1991. If it was all used, then she just gets �300K. If none of it was used, then she gets 2 lots of �300K. If half of it was used she gets her �300K plus another half of �300K - ie �450K. It depends on the PROPORTION of the husbands allowance that was used, not the actual amount.