A record number of U.S. taxpayers renounced their citizenship or green cards in 2013, according to new data.

Each quarter the U.S. Treasury publishes the names of the Americans who officially expatriated during that period. In the last quarter of 2013, 630 people renounced their citizenship or relinquished their green cards, added to the previous 2013 quarters (2,369 people), brining the total for 2013 to 2,999.

According to Andrews Mitchel, an international tax attorney who tracks the expatriations at his International Tax Blog, the 2,999 amount represented a 221 percent increase over the 932 total in 2012 — and “shatters” the previous record of 1,781 set in 2011.

Mitchel points to three possible reasons for the increase in expatriations last year.

“Increased awareness of the obligation to file U.S. tax returns by U.S. citizens and U.S. tax residents living outside the U.S.,” he writes. “The ever-increasing burden of complying with U.S. tax laws; and [t]he fear generated by the potentially bankrupting penalties for failure to file U.S. tax returns when an individual holds substantial non-U.S. assets. The increase in expatriations may also be partly due to a 2008 change in the expatriation rules.”

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