Conservative Leader Stephen Harper is promising up to $150 annually in added tax relief for seniors if his party is re-elected.

Harper said his government would increase the Senior Age Credit by $1,000. Seniors in the lowest tax-paying income bracket would receive the maximum of $150 in savings.

"We should do more to let seniors keep more of their hard-earned dollars," Harper said during a campaign stop in Trois-Rivieres, Que.

He called the tax relief "modest" but "affordable, responsible and credible."

In total, the measure would cost federal coffers about $400 million a year, say the Tories.

Harper also promised to change a decade-old Liberal tax initiative.

In 1997, the Liberals changed the rate at which the government taxed U.S. social security benefits paid to Canadian residents.

The result was that about 85,000 Canadian seniors were forced to pay higher taxes then expected when planning their retirement, said Harper.

"If re-elected, our Conservative government will offer complete tax relief to seniors affected by this problem," he said.

NDP Leader Jack Layton also targeted seniors Thursday, announcing a $1-billion home-care program.

Layton said his government would pay to allow 100,000 more seniors to be cared for in their homes instead of institutions.

"As prime minister I will stand up for seniors, helping them to live with dignity in their home for as long as possible," Layton said in Winnipeg, alongside Manitoba Premier Gary Doer.

The program would cost $250 million in the first year and grow to $1 billion by the fourth year, said the NDP.

"Canada's senior citizens built this country, and we're all in their debt," said Layton. "It's time that a Prime Minister began to repay that debt and honour that contribution."

As health care is delivered on the provincial level, Layton said each province would negotiate deals with Ottawa.

With files from The Canadian Press