The rate detailed on any Aegon Scottish Equitable annuity quote will now be guaranteed for at least 21 days, up from 14 days.
If the rate increases, the new higher rate will automatically apply. But if the rate decreases, it will remain guaranteed for a further period of 21 days from the date of the reduction.
Mark Cardy, head of annuity sales at Aegon Scottish Equitable, said: "Our distributors have told us that one of their biggest frustrations in dealing with a client’s annuity is the time and effort it takes to re-quote to keep the rate current whilst waiting for the case to complete.
"We have therefore increased our guarantee period on all annuity quotes from 14 days to at least 21 days. If there is a rate decrease within 21 days from quote, the original higher rate will now be guaranteed for a further 21 days from the date of a rate decrease.
"If the rate increases within 21 days from quote, clients will automatically receive that higher rate."
Last month the firm, also introduced a investment control offshore bond and is set to launch a flexible version of its flexible retirement product 5 for Life.
