U.S. real estate commissions have fallen by 34% since earnings peaked in 2005. But Orange County real estate brokers saw their take-home pay fall further from peak levels, declining by about 50% from ‘05 levels.

ForSaleByOwner.com estimates that U.S. real estate commissions fell to $46.6 billion in 2008, down 34.6% from $71 billion in 2005 — the peak year for agent and broker earnings.

Orange County’s likely commission total, based on data from two sources, ranged from $801 million to $845 million.

The SoCal MLS has reported that revenue generated by O.C. home sales totaled $13.3 billion. Assuming a commission rate of 6% (it actually varied between 5.2% and 6% in recent years, according to brokers), then total O.C. commissions were in the neighborhood of $801 million last year, vs. $1.5 billion in 2005. That’s a drop of 47%.

Separate estimates by DataQuick put the revenue total at $14.1 billion, although their data includes all home sales, including those not handled by brokers. Six percent of that revenue total is $845 million, down 54% from 2005 levels. O.C. sales revenues fell to their lowest level last year since 2000, DataQuick figures show.

ForSaleByOwner.com blamed last year’s decrease on falling home values.

The average U.S. commission was $12,600, the web site reported. The West had the highest average: $16,230 per sale.

Based on figures from both SoCal MLS and DataQuick, the average O.C. commission in 2008 was just under $35,000.