James Bopp, an attorney for the Colorado Springs-based conservative Christian group, said the group has fully complied with IRS code.
The complaint, filed Monday by Citizens for Responsibility and Ethics in Washington, also asked the IRS to investigate whether the tax-exempt status of Focus on the Family should be revoked. Tax-exempt organizations cannot participate in campaigns for or against candidates for public office.
The group alleges that news articles showed Dobson endorsed candidates for Congress before the organization officially formed its separate public policy arm, Focus on the Family Action, in July 2004.
Bopp said the organization didn't break any rules.
"Anything Dr. Dobson did to endorse candidates, he did as an individual," Bopp said.