Here are few websites we think will be useful for you.

Internal Revenue Service
   - Main Page
   - Make A Tax Payment
   - Get Tax Record/Tax Transcript
   - Taxpayer Online Account
   - EFTPS Business Tax Deposit

State of Washington
   - Secretary of State Corporation Division (Annual Report, Incorporation and LLC Formation)
   - Department of Licensing (Business License Application)
   - Secure Access Washington (Tax Return Filing for WA Department of Revenue, Employment Security Department, Department of Labor & Industries, etc.)
   - King County Department of Assessments (Personal Property Tax Affidavit Filing and Real Estate Property Tax Payment)
   - File-Local (City B&O Tax filings, including Seattle, Bellevue, etc.)