“Besides the 1040 and IT-201 for individual tax, do I need to file additional tax report because I'm a share holder for the 'B' company?”---->As you can see, your S corp. is similar to a partnership, in that the taxable income or loss of the S corporation flows through to you, the shareholders, that report the income or loss on your own tax return. However, as shareholder-employees , you and your buddy should prepare both federal S corporation tax returns by filing Form 1120 and state S corporation tax returns, Form CT-3-S, for the business. An S-corporation is not subject to corporate tax rates. "Generally, an S corporation is exempt from federal income tax other than tax on certain capital gains and passive income. However, some states recognize the federal S election and treat the corporation the same way for state tax purposes. Other states don't recognize the election at all and tax the business as a regular corporation. For example, the DC franchise tax applies not only to C corps. and S corps. but also to most unincorporated businesses. Though, in general, your S-corp itself does not pay taxes on its income, it must still calculate its taxable income, as that information is necessary for you to determine you and your buddy’s tax obligations. The business profits are taxed at your individual tax rate on your Form 1040. I mean you, as shareholders of your S corp, pay the corporation's taxes based on your pro-rata share of the business. The pass-through nature of the income means that your corporation's profits are only taxed once – at the shareholders’ marginal tax rates.
“Such as schedule C ?”----> You do not complete Sch C or Sch SE as S corp shareholder-employee, but are subject to withholding taxes,i.e., FICA taxes or etc on your W2.
“Or just adding W-2 form from 'B' company, even if there wasn't any payroll, for the individual tax report suffice?”---->Correct; as said above. You need to report your income on your W2 on 1040 line 7.If your S-corporation retains its net profits ( if it has) as operating capital , then, all profits are considered as-if they were distributed to you, shareholders. Thus you might be taxed on income you never received. A distribution of profits from your S corp. is not subject to FICA taxes, unemployment taxes, workers' compensation taxes or other expenses associated with salary. You need to consider state taxes. S corporations might have specific filing requirements in the states in which they are registered, as well as in any states in which they conduct business. As is the case for any other corporation, the FICA tax is imposed only with respect to employee wages and not on distributive shares of shareholders. Although FICA tax is not owed on distributive shares, the IRS and equivalent state revenue agencies may recategorize distributions paid to shareholder-employees as wages if shareholder-employees are not paid a reasonable wage for the services you perform in your positions within the company.
I have spent $2,000 for the medical insurance last year (as a voluntary adjustment which they deduct this amount before tax ). Is it deductible anyway as a 'medical' expense?”---->I guess it depends on the situation; if your medical expenses are qualified , then the Medical expenses can be deducted on a tax return if they exceed 7.5 percent of your AGI. However, if you do not claim your itemized deductions on 1040 Sch A, then you can’t deduct’em.
“I have spent $5,000 repaying for the student loan last year. Out of that amount $450 was an interest. In that case only $450 is tax deductible correct?”--->Correct; you can deduct student loan interest on Form 1040 line33.
-“For the 30% sahre of 'B' company, I have contributed $2,500 . Is this amount tax deductible in any way?
“ ----> I don’t think so; your cash contribution to the S corp’ is just basis of your share; your capital account needs to reflect your investments(contributions) and current basis in the S-Corporation's equity or liabilities.