Em healthcare.gov :
U.S. citizens living in a foreign country for at least 330 days of a 12-month period are not required to get health insurance coverage for that 12-month period. If you're uninsured and living abroad under this definition, you qualify for a health insurance exemption for plan years 2018 and earlier. This means you don’t have to pay the fee that other uninsured people must pay when they file their taxes.
Note: Starting with the 2019 plan year (for which you’ll file taxes in April 2020), the fee no longer applies. If you don’t have coverage during 2019 or later, you don’t need an exemption in order to avoid the penalty.
Portanto, para este ano, se você estiver fora do país por pelo menos 11 meses, você não precisa de um seguro de saúde sob a ACA. A partir do ano que vem, o requisito de seguro da ACA foi eliminado, portanto não há penalidade por não obter seguro de saúde.