Record average home sales prices in the Hamptons set during the fourth quarter of 2012 are being attributed to a year-end sell-off of multimillion dollar properties — so the owners could get sales on the books before higher taxes were imposed Jan. 1, 2013.

Douglas Elliman’s quarterly report places the average sales price in the Hamptons market at $2,130,788, the highest level since the firm began tracking the data seven years ago. Brown Harris Steven’s quarterly report states that the average was even higher, $2,171,928, though the report considered 345 South Fork single-family home sales, while the Douglas Elliman report looked at 529 property sales.

Those 529 sales mean that sales volume shot up 30 percent, year-to-year, in the fourth quarter, according to Douglas Elliman. “The final quarter of the 2012 Hamptons housing market was characterized by unusually heavy sales volume and falling inventory, which both hit six-year highs and lows, respectively,” the report states.

“Facing higher capital gains taxes and a new 3.8 percent Medicare surtax on investment income, many high-end sellers rushed to close on the sale of their Hamptons home in the fourth quarter of 2012,” wrote Gregory Heym, the chief economist of Brown Harris Stevens, in the firm’s report.

Heym said the rush to sell high-end homes is reflected in the number of closings for homes at $2.5 million or more rising 98 percent compared to the fourth quarter of 2011. “Overall, the total number of sales rose 16 percent from last year,” he added.

“This also led to large increases in both the average and median price on the South Fork,” he said. “At $2,171,928, the average price was 27 percent higher than the fourth quarter of 2011, while the median rose 16 percent to $975,000. East Hampton saw the biggest effect on its statistics from the increased luxury activity, as its average price more than doubled from the fourth quarter of 2011.”

In the Southampton market, the median home sales price increased 19 percent, to $1,378,900, according to Brown Harris Stevens. The average price grew 20 percent to $2,604,181.

In the Westhampton market, the median dropped 15 percent to $425,000, while the average price grew 4 percent to $895,141.

The East Hampton market, including East Hampton Village and unincorporated East Hampton, saw the biggest spike in its average price — 103 percent from the fourth quarter of 2011 to the fourth quarter of 2012. The median price rose 33 percent to $937,500. The total number of sales grew 27 percent, whole sales for more than $1 million doubled, according to Brown Harris Stevens.