The legacy rate is a progressive tax rate on prefs that expire when a citizen account is closed due to death.
10% First 10,000 Prefs
25% 10001-100,000 Prefs
55% 100,001 - 1,000,000 Prefs
85% Over 1,000,000 Prefs
These are per originating account. The percentages taken should be taken in proportion to the ownership before the tax is supplied.
For example, if the account owns 10,000 prefs in account X and the account prefs are split 70%/30% between two different accounts, the 10% would be taken, leaving 900 prefs to be split 70/30 between the inheritors.