They had been arguing for years, and now it was time to call it quits.

So in late June, the Northern Virginia Mental Health Association broke away from its parent organizations, the Mental Health Association of Virginia and the national Mental Health Association.

The reason, as in many breakups, was money.

The local chapter says it had been charged excessive dues, while the state chapter maintains that Northern Virginia's share was determined by an accepted formula voted on by local chapters nationwide.

The national Mental Health Association is supported by dues from its state divisions and local chapters. Its annual budget of about $1 million supports lobbying efforts for mental health concerns in state legislatures and in Congress, research and publication of literature on mental health, among other activities, according to spokesman for the national association based in Rosslyn.

Local chapters, besides contributing to these activities with dues payments, also conduct their own local programs.The Northern Virginia Mental Health Association runs a citizen advocacy program in which volunteers befriend a mentally disabled persons in one-to-one relationships: it has a speakers bureau: it conducts vocational rehabilitation programs for persons who are reentering society from an institution, and it refers the mentally ill to local treatment centers, among other projects.

The local association, which has 39 local residents on its board of directors, serves Arlington, Fairfax, Falls Church and Fairfax City,. It has been affiliated with the state association more than 20 years.

"We're going to continue operating just as we did before." said Leah Porzel, president of the Northern Virginia Mental Health Association. "We will offer the same services as we always have, and probably others."

John Redstrom, executive director of the state association, which represents the national association, says Northern Virginia's disaffiliating "weakens both us and them.

"For a local chapter to direct attention only at its own area ignores the bigger picture," Redstrom said. "It weakens the impact we have as an organization to change conditions for the mentally ill.

"As far as the local chapter is concerned, it will no longer receive information of what's going on in Congress or information on new trends in treatments and services for the mentally ill," Redstrom continued.

But Porzel sees more advantages than disadvantages in going solo.

"The biggest advantage of course is not having all of those dues to pay," she said. "We can put that money into our own community. We can live without the association's logo and print our own literature."

She admitted, however, that there is some fear the national organization will start another branch in the Northern Virginia area, as indicated by a letter sent from the national association to the Northern Virginia chapter shortly before it voted to break away.

The dues payment dispute began seven years ago, since the national association went to a formula of assessing the amount of dues owed by each local chapter. Taken from a national marketing magazine. Sales Management, the formula determines the effective buying index (EBI), or the amount of available dollars to spend after taxes, for each locality.

Redstrom said Northen Virginia's EBI for 1977 is about 22.45 per cent and that is the percentage the area would have been expected to contribute toward the state's current budget of $102,000.

As it is, they won't be paying anything since they broke away," Redstrom said.

Porzel says the Northern Virginia chapter has been expected to pay nearly 30 per cent of the state association's budget within the last seven years, about $113,000. But the chapter only paid about 1/6 of the total budget, said another spokesman for the local chapter.

Redstrom said Northern Virginia's share of the state association's budget has only been about 20 per cent during the past seven years. He said the chapter had been assessed $110,593 in dues, but only paid $51,000.

Last year, the chapter's share of the state association's 1976 budget of $85,000 was assessed at $16,461. Redstrom said. The chapter paid $11,000, he said.

Porzel said the local chapter was already strained by the dues it did manage to pay to the state.

"As United Way members, we were only allowed one fundraising drive on our own and our dues were more than we could raise in that drive," she said. "United Way forbids dipping into United Way funds to pay dues, which would mean local funds would be sent out of the community. We were caught in a bad position."

Last year's budget for the local chapter was $50,000, about 90 per cent of it from United Way. The chapter's membership drive raised $5,000.

"We just didn't have the money to pay $16,000 in dues last year," Porzel said. "And it's been the same thing every year. This disaffiliation came as no surprise; everyone had been expecting it for a long time.

Redstom said the Richmond area chapter broke away from the state organization about 10 years ago: "It was the only chapter that left the organization before Northern Virginia, as far as I know.

"We've had financial disputes with other chapters in the state, but never to the extent of this chronic problem with Northern Virginia," Redstrom said. "We regret they are leaving, but we respect their right to do so."