Australia: Australian Taxation Office:

• Main site

Kanada:

• Laws
• Canada Revenue Agency:
  • Main site
  • Deductions index

United Kingdom: Hasil dan Kastam KDYMM:

• Main site
• HMRC manuals
  • Business Income Manual (BIM)

Ameriia Syarikat: Internal Revenue Service:

• Main site
• Some relevant publications:
  • 334 Business expenses: Tax Guide for Small Business
  • 463 Travel and entertainment deductions
  • 501 Exemptions and standard deduction
  • 529 Miscellaneous deductions
  • 565 Business Expenses
  • 936 Home mortgage interest
  • 946 Depreciation
• A few relevant forms (also see related instructions)
  • Form 1040 (individual tax return), Schedules C (business) and E (rental)
  • Form 1065 (partnership return of income), page 1, and Schedule K
  • Form 1120 (corporation tax return), page 1
  • Form 2106 (employee business expenses)
  • Form 4562 (depreciation and amortization)
  • Form 4797 (gain or loss on business assets)
  • Form 8825 (rental realty income)

India:

• Official page of Indian Income-tax e-Filing portal