Several links are provided below for general information and proper tax planning:

Tax Information For Businesses
IRS Small-Businesses-&-Self-Employed Homepage
IRS Audits
IRS Audit Techniques Guides (ATGs)
ATG for Cash Intensive Businesses
A-Z Index for Business
Affordable Care Act (ACA) Tax Provisions for Employers
Business Structures
IRS Tax Calendar for Businesses and Self-Employed
Form 1120”S” Corporations
S Corporation Compensation and Medical Insurance Issues
Operating a Business
Businesses with Employees
Independent Contractor (Self-Employed) or Employee?
Estimated Taxes
Employment Taxes
Notice from the IRS
IRS Notices: Understanding Your IRS Notice or Letter
Taxpayers with Offshore Accounts
Report of Foreign Bank and Financial Accounts (FBAR)
Penalties and Interest, IRS Penalty Relief Handbook, Reasonable Cause Relief Provisions – Link 1 and Link 2