Rearranging the letters of 'A retirement plan' gives:
Enter parliament.
(by Hans-Peter Reich using Anagram Genius) (2006) (pending approval)
Other related anagrams without their own page:
"Retirement" -> "Entire term." (by William Tunstall-Pedoe using Anagram Genius) (2001)
"Retirement" -> "Enter merit." (by William Tunstall-Pedoe using Anagram Genius) (2001)
"Obama tells elderly he will protect retirement" -> "Well treatment as mercy, help to old? Terrible lie!" (by Pinchas Aronas) (2008) (pending approval)
"Old Age Pensioner" -> "Plead, "Gone senior!"" (by Tony Crafter using Anagram Genius) (2004)
"Old Age Pensioner" -> "No glee: diaper's on." (by Mike Mesterton-Gibbons by hand) (2004)
"Old Age Pensioner" -> "One so ripened gal?" (by Mike Mesterton-Gibbons by hand) (2004)
"Old Age Pensioner" -> "A loser needing op." (by V.Rabin) (2004)
"Old Age Pensioner" -> "Ordeal: penis gone." (by Joe Fathallah) (2003)
"Old Age Pensioner" -> "Ignored? Please, no!" (by David Bourke using Anagram Genius) (2002)
"Old Age Pensioner" -> "Ideal person . Gone." (by Rick Rothstein using Anagram Genius) (2002)
"Old Age Pensioner" -> "Senile. (Danger: Poo!)" (by David Bourke by hand) (2000)
"Old Age Pensioner" -> "Reside alone...pong." (by David Bourke by hand) (2000)
"Old Age Pensioner" -> "A person gone idle." (by Jason Lofts) (2016) (pending approval)
"Old Age Pensioner" -> "Idle one, a sponger." (by Jason Lofts by hand) (2016) (pending approval)