Canada's high court says child-support payments should reflect the income of the parent paying them.

The unanimous ruling yesterday means that parents -- usually the father -- who conceal their incomes to avoid higher payments, now face massive retroactive judgments.

It's a decision that has single fathers' groups crying foul and women's advocates applauding.

Danny Guspie, executive director of Fathers' Resources, a support group for fathers that has chapters in Hamilton and Toronto, said the disclosure will financially handcuff parents for life. And he doubted courts will reduce payments if incomes fall.

"It's always been a problem," he said. "It's easier to increase payments than decrease them."

Women's groups are cautiously optimistic.

"Anything that moves towards any open discussion of family assets is a step in the right direction," said Sally Littell, executive director of the Women's Centre of Hamilton.

She said women often carry the burden of child rearing and are forced to take time off work, putting them behind in their careers. When they do return to work, it's often for lower wages and courts need to take that into account.

But she said children should be the first priority.

"If a parent does better, it's important that their children do better as well," Littell said.

The ruling stems from the appeals of four retroactive judgments made against Alberta men.

The Supreme Court ordered two of them to pay up, while the other two were absolved based on the circumstances of their cases.

Hamilton family lawyer Michael Clarke said the ruling will change many of his clients' situations.

"It's something I've believed for a long time," he said. "If payers are making more money, they should report it. They have an obligation to their children."

Until now, Clarke said the onus has been on the parent receiving child support to request more money. Lawyers would have to include a clause in the support agreement to have the payer disclose his or her earnings.

Clarke said his office has been waiting on the ruling for one case where a father is making more than $1 million annually and still paying child support according to his former $150,000 salary. Clarke said his client plans to ask for payments to be made retroactively.

"My client will be very happy," he said.

The legal principles laid out by the high court could have a wide-ranging impact. There are an estimated 700,000 child support orders across Canada, with a dollar total in the hundreds of millions, if not billions.

The basic rule under federal law is that "parents have an obligation to support their children in a way that is commensurate with their income," said Justice Michel Bastarche, writing the main opinion.

"A payer parent who does not increase his-her child support payments to correspond with his-her income will not have fulfilled his-her obligation to his-her children."

The wording reflects the gender-neutral language of the law. But the overwhelming majority of parents paying child support are male and the overwhelming majority of recipients female.

Three other judges joined Bastarche in his legal reasoning. The remaining three concurred in the result, but for different legal reasons.

The judgment doesn't mean that every claim for retroactive payment will automatically be granted.

For example, a father with a low income, or who has remarried and has a new family to support, may face undue hardship paying a lump-sum award.

In contrast, a man who deliberately conceals an income increase to avoid paying more in child support will likely end up on the hook for the extra cash.

When a retroactive award is warranted, Bastarche said, the rough guideline is that it usually shouldn't go back more than three years.

Guspie said many times fathers lose their jobs or are forced to take on new employment with lower earnings, but the child support payments aren't adjusted accordingly.

"All of a sudden, they are in arrears and they're deadbeats," he said.

"Child support guidelines are skewed. The amounts aren't realistic. By the time all is said and done... they end up sleeping in their cars."

bMcKay@thespec.com

905-526-4629

With files from Canadian Press