This is part of the Affordable Care Act. Because of the ACA, everyone must have insurance, either through their employer or purchased through one of the marketplaces (i.e. personally purchased).
Here is the blurb about fees for not being covered:
https://www.healthcare.gov/fees/fee-for-not-being-covered/
If you can afford health insurance but choose not to buy it, you must
pay a fee called the individual shared responsibility payment. (The
fee is sometimes called the "penalty," "fine," or "individual
mandate.")
You owe the fee for any month you, your spouse, or your tax dependents
don’t have qualifying health coverage (sometimes called "minimum
essential coverage"). See all insurance types that qualify.
You pay the fee when you file your federal tax return for the year you
don’t have coverage.
In some cases, you may qualify for a health coverage exemption from
the requirement to have insurance. If you qualify, you won’t have to
pay the fee. Learn about health coverage exemptions.
Learn more about the individual shared responsibility payment from the
Internal Revenue Service.
The fee for not having health insurance in 2016 & 2017
The fee is calculated 2 different ways – as a percentage of your
household income, and per person. You’ll pay whichever is higher.
Percentage of income
2.5% of household income Maximum: Total yearly premium for the national average price of a Bronze plan sold through the Marketplace
Per person
$695 per adult $347.50 per child under 18 Maximum: $2,085 Paying the
fee
Using the percentage method, only the part of your household income
that’s above the yearly tax filing threshold ($10,300 for individuals,
$20,600 for couples filing jointly in 2015, the most recent year
available) is counted.
Using the per-person method, you pay only for people in your household
who don’t have insurance coverage.
If you have coverage for part of the year, the fee is 1/12 of the
annual amount for each month you (or your tax dependents) don’t have
coverage. If you’re uncovered only 1 or 2 months, you don’t have to
pay the fee at all. Learn about the “short gap” exemption.
You pay the fee when you file your federal tax return for the year you
don’t have coverage.
You can use their tool to determine if you are exempt from coverage:
https://www.healthcare.gov/exemptions-tool/#/
Also, your $15K income is taxable, FYI. You'll be in a low tax bracket, but you will still be paying taxes.
Update based on additional information provided in the comments:
1. Does the tax penalty due to having no health insurance apply to a resident alien defined for tax purpose?
Yes. This applies to resident aliens.
- Are all individuals living in the United States subject to the individual shared responsibility provision?
All U.S. citizens living
in the United States are subject to the individual shared
responsibility provision as are all permanent residents and all
foreign nationals who are in the United States long enough during a
calendar year to qualify as resident aliens for tax purposes. This
category includes nonresident aliens who meet certain presence
requirements and elect to be treated as resident aliens. For more
information see Pub. 519.
2. Does the tax penalty due to having no health insurance apply to 2016?
Yes. When you file your 2016 taxes (which are due by mid-April 2017), you will need to prove you either had insurance or were exempt from needing insurance in 2016.
3. I might start to work from mid Jan this year, which should provide health insurance. Will I receive tax penalty for not having health insurance during the first half of Jan in 2017?
Yes. You have a 3 month grace period for not having insurance. In order to avoid the penalty, you will need to have insurance coverage until your company's insurance kicks in. You should read this to get more info about the grace period, as you might not need to pay for more than a month or 2 to get into the grace period.