The Democrat and Republican candidates for the vacant seat on the Fairfax County Board of Supervisors have far outspent the independent candidate, aided by contributions from incumbent officeholders and political action committees, financial reports filed yesterday show.

The campaign for the pivotal seat on the nine-member board has become one of the most expensive district supervisors races ever. The spending has been spurred by circumstances that could give Republicans control of the county board for the first time since Reconstruction.

Republican attorney T. Farrell Egge's campaign is ahead in contributions, collecting $46,613. Records show his campaign has spent $34,361. The campaign owes $836 in loans, reports show.

Democrat Gerald W. Hyland, also an attorney, has raised $28,239 and has spent $27,083. Reports show his campaign has $11,787 in outstanding loans.

The campaign financial disclosure reports show that independent Gerald A. Fill, a member of the County School Board, has $5,147 in contributions and has spent $10,241. Fill's campaign also has $11,864 in outstanding debts.

Both Egge and Hyland have received substantial contributions from elected officials within their own parties. Republican Supervisor Thomas M. Davis III has donated $2,000 to Egge's campaign, coupled with a $1,000 contribution from Davis' employer, Advanced Technology, Inc. Supervisor Nancy K. Falck has given Egge $1,100 and Sheriff Wayne Huggins contributed $250, reports show.

Hyland's contributions include $200 from state Sen. Joseph V. Gartlan and $150 from state Sen. Clive L. Duval, both Democrats. Hyland also has received major contributions from unions and similar associations, including the Fairfax Education Association, which gave $1,000; a local firefighters PAC, $500; International Brotherhood of Electrical Workers Educational Committee, $500; and the International Brotherhood of Painters and Allied Trades, $1,350 in-kind contribution.

One influential local PAC, the Northern Virginia Builders Association Affordable Shelter PAC, gave $300 to both the Egge and Hyland campaigns. The Richmond-based Realtors PAC contributed $750 to the Egge campaign.

Fill itemized only three contributions over the $100 reporting minimum required by state law. Those included $2,200 from Springfield contractor William A. Moore and a $795 personal contribution.

The preelection financial disclosure reports reflect contributions and expenditures for campaign for the period that ends eight days prior to the election.

The Mount Vernon seat was vacated last summer when Democrat Sandra L. Duckworth resigned to join her husband in his new job in Honolulu. Her unexpected resignation set off a frenzied effort in both political parties to attempt to capture the seat and spawned the independent candidacy of Fill, who was Duckworth's appointee to the School Board.