It means only a modest amount of additional income is already pushing low-income pensioners past the frozen £12,570 tax-free threshold.
Pensioners who rely solely on the state pension are expected to pay tax on their income by 2027, according to a separate analysis by Deloitte.
Jon Greer, head of retirement policy at Quilter, said low-income pensioners risked being “ensnared in a stealth tax trap” if the Chancellor chose to extend the freeze.
He added: “Thresholds that are meant to shield lower earners are stealthily morphing into a tax burden for those on the lowest incomes.
“This rumoured extension would mean that, by 2030, over one million pensioners could see their hard-earned savings chipped away with unexpected tax bills, making it increasingly difficult for them to manage their finances at a time when every penny counts.
“It highlights just how damaging this freeze could be if it continues beyond its current timeline.”
The Treasury was approached for comment.