Liberal Democrat councillor Ben Lawrie said that 18,559 state pensioners in the county are set to be affected by the change.
The state pension triple lock is a rule that means the state pension must rise each year in line with the highest of three possible figures - inflation, average earnings or 2.5%.
It follows a recent vote in Parliament in which Conservative MPs voted to suspend the triple lock, despite a manifesto commitment to keep the triple lock in place until 2024, and after a tax hike on National Insurance.
The Liberal Democrats have warned that the Conservatives are “turning their back on local elderly residents,” many of whom are living in poverty.
The figures, based on analysis by the House of Commons Library, show that 21.6% of people in Angus will be hit. They also show that 2375 pensioners in the area are benefiting from state Pension Credit, which is given to the poorest pensioners.
Mr Lawrie said: “This is yet another broken promise from the Conservatives that will hit pensioners in Angus hard in the pocket.
“The government is turning its back on local elderly residents, who risk no longer being able to heat their homes this winter as energy costs spiral.
“Our pensioners deserve a fair deal. The triple lock was a cast iron guarantee that vulnerable elderly people were relying on and the Conservatives have failed them.”
“Liberal Democrats are demanding that the government supports the many pensioners in our area living in poverty and ensure that we don’t return to the days of the 75p rise to the state pension.”
The Liberal Democrats tabled an amendment in Parliament to the Social Security Bill that called for additional support to address the impact of the pandemic on the two million pensioners currently living in poverty and making the uplift to Universal Credit permanent. Labour abstained on the vote, making the Liberal Democrats the only major UK-wide party to stand up for pensioners and oppose the government’s broken promise to them.