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

Help and Resources page from irs.gov
Your Appeal Rights
Appealing a Collection Decision (CAP, CDP, OIC and TFRP)
IRM: Internal Revenue Manual Index – The IRS internal processes and procedures are contained in the Internal Revenue Manual (IRM) section 4 for Examination, section 5 for Collection, section 8 for Appeals, section 20 for penalties and interest, and section 25.15 for innocent spouse.
A Notice from the IRS
IRS Notices: Understanding Your IRS Notice or Letter
irs.gov
Taxpayer Bill of Rights (June 2014) – In June 2014 the IRS published a new list of Taxpayer Rights. Each and every taxpayer has a set of fundamental rights they should be aware of when dealing with the IRS. Explore your rights and our obligations to protect them.
Innocent Spouse – Divorce happens. Understand your rights and responsibilities for IRS tax problems and the three types of innocent spouse relief available. See Form 8857 and Instructions. Also see IRM section 25.15. Injured Spouse claims are filed on Form 8379.
Taxpayer Advocate Service
NAEA: Find An EA
NAEA: Why Use an Enrolled Agent?
EFTPS: The Electronic Federal Tax Payment System
IRS Freedom of Information Act (FOIA)
IRS Current Tax Tips
Transcript of Your Account
Affordable Care Act (ACA) Tax Provisions
Health Care Tax Tips
IRS Tax Helper Assistant
IRS Audits
IRS Audit Techniques Guides (ATGs)
IRS ATG for Cash Intensive Businesses
Circular 230 – Rules Governing Practice Before the IRS – Enrolled agents are required to adhere to the Code of Ethics and Rules of Professional Conduct by the Circular 230 regulations.
Penalties and Interest, IRS Penalty Relief Handbook, Reasonable Cause Relief Provisions – Link 1 and Link 2
Taxpayers with Offshore Accounts
Report of Foreign Bank and Financial Accounts (FBAR)