I'm a foreign national in the US (came here mid-August 2018 on valid non-immigrant US visa and it's been more than 180 days from then) and recently I signed up for a bank account and got a signup bonus of $300 (There is no other amount credited into this account yet like salary). What is the tax liability on me? And what is the process to be followed as the bank did not withhold any tax at source or provide me with any tax-related form while opening the account. Please advise.
This is considered taxable income.
At the end of the year, the bank will send you (and the IRS) a form 1099-INT, which contains this amount. You will have to add it to your tax declaration, and it might or might not result in your taxes being slightly higher, depending on what other income you have. (In any case, the tax increase is significantly less than those 300, so it is a deal).