The House Financial Services Committee formally approved an amendment this morning to exempt small companies from Section 404(b) of Sarbanes-Oxley.

On a 37-32 vote—that, notably, went against the wishes of powerful committee chairman Rep. Barney Frank—the lawmakers approved an amendment to the Investor Protection Act that would exempt all non-accelerated filers from Section 404(b). The committee then went on to approve the entire Investor Protection Act by a vote of 41-28.

The amendment reportedly represents a compromise between anti-SOX lawmakers, who wanted to exempt a much larger group of filers, and the Obama Administration. But financial reporting executives shouldn’t rejoice yet: The bill must still be approved by the full House and then by the Senate to become law.

Section 404(b) requires companies to get an auditor’s attestation about the effectiveness of their internal controls over financial reporting and is widely considered the biggest compliance burden in the Sarbanes-Oxley Act. Large filers have had to comply with the provision since 2004, but the Securities and Exchange Commission has repeatedly extended the compliance deadline for non-accelerated filers.

The amendment, sponsored by New Jersey Reps. John Adler and Scott Garrett, also directs the SEC and the Comptroller General to conduct a joint study to determine how the SEC could reduce the burden of complying with Section 404(b) for companies with market caps between $75 million and $250 million.

Even if the measure does ultimately become law, non-accelerated filers (and everyone else) will still need to comply with Section 404(a), which requires companies to review and disclose the state of their internal controls. Section 404(a) went into effect for non-accelerated filers one year ago.

The committee’s action follows the SEC’s Oct. 2 announcement of one final delay for non-accelerated filers. Under that delay, the smallest public companies are supposed to begin complying with the provision beginning with their annual reports for fiscal years ending on or after June 15, 2010. The extension was granted at the same time the SEC released its study on SOX compliance costs and benefits.

An SEC spokesman said the Commission had no comment on today’s action by the committee, but referred to a letter sent by chairman Mary Schapiro on Oct. 16 to capital markets Sub-committee Chairman Paul Kanjorski.

That letter noted that, “According to our staff’s recent study of the costs and benefits of Section 404, surveyed investors indicated that Section 404 compliance ‘has significantly impacted their confidence in companies’ financial reports’ … Investors indicated that they have greater confidence when a Section 404 audit is performed.”

“... I believe that the enactment by Congress of Section 404 continues to significantly improve investor confidence in the integrity of companies’ financial reports and reporting,” Schapiro wrote.