The current shareholding guideline for executive directors, including the CEO and CFO, is two times salary, Shell said.
Jeroen van der Veer, who retired as chief executive in June 2009, received total compensation of $15 million for 2008, according to Shell's annual report.
Voser, who was chief financial officer until he took over in July, earned $6 million.
Shell's London-listed "A" shares were not affected by the news, trading up 0.8 percent at 1,741 pence at 2:44 p.m., compared to a 0.4 percent rise in the DJ Stoxx European oil and gas sector index <.SXEP>.
(Reporting by Tom Bergin; Editing by Erica Billingham, Louise Heavens and Karen Foster)