I'm not a US citizen but I've been living and working as a computer engineer in US on a work visa (OPT) for the past ~3 years and previously went to a university in the US as well. Based on the duration of my stay, I am a tax resident and have been paying taxes accordingly for the past few years (I live in Florida so there's no state income tax).
In my full-time job in Florida I make $60k/year. My employer withholds taxes including Social Security, Medicare and Federal Income Tax and provides me with a W2.
In late April 2017, I started a remote contracting job (on top of my current job) for a company from London. This job will pay me $2500/month ($25/hr for 100hrs/month) for 5 months (May, Jun, Jul, Aug, Sep), which is an additional $12,500.
This puts my total gross income for 2017 at $72,500, which still leaves me in the 25% tax bracket (I'm single).
My UK contracting job doesn't withhold any taxes. I've never held a contracting job before and I've had little luck figuring out how this affects my tax situation, considering I also have a full-time job.
How do I pay taxes on this extra income from the UK job?
- Which forms are needed?
- How do I know how much I should pay? Currently I'm just not spending any of this extra income until I figure out what to do.
- Through my research I found that I should probably pay quarterly installments, is this true? If so, when should I pay them and with which forms?
- Do I not need to pay Social Security and Medicare again?
- Any advice on how do I figure out what deductions I can have?
Any help is much appreciated!