However, before making this decision, you should be aware that individuals rescinding their US citizenship after June 2008 may be subject to considerable US income tax upon
expatriation. In addition, gift tax may be imposed on the recipient of a gift from an expatriate. Unless you qualify for a specific exception to the rules, the “exit tax” provisions are imposed on expatriating individuals who meet any one of the following criteria:
1. Have a net worth over $2 million on the date of expatriation, or
2. Average US income tax liability for the 5 years preceding the date of expatriation exceeds a certain amount that is indexed to inflation (US$155,000 for 2013), or
3. Have not complied with all US federal tax obligations for the 5 years preceding the expatriation date.
BMO Nesbitt Burns: US Citizens Living in Canada, Income Tax Considerations
As someone not even close to being a US constitution wonk, there may be others here better at analyzing what William Thomas Worster of the Hague University argues is unconstitutional about the US’s exit tax:
Thank goodness we’re “poor” and don’t have assets that amount to over $2m. I guess she can slide out quickly without too much of a financial hit.