Benefits:
Buy a condo without having to transfer money from abroad.
You can become a director of a public company.
You can apply for an extension of stay for a non-Thai family
Stay in Thailand permanently without a visa. Yeah,
Circumvent visa runs, red tape and extended stays.
Obtain a work permit quickly and easily.
Obtain a permanent residence book and alien registration book.
Improve your chances of acquiring mortgage financing.
Get one step closer to citizenship.
Qualifications:
To become eligible to apply for Permanent Residency Permit, the applicant must meet any of the following criteria:
Must hold 3 consecutive 1-year visa extensions.
Must have a valid work permit for 3 years at the date of application.
Must earn 30,000 Baht monthly income (for those married with Thai spouse for 5 years) and 80,000 Baht monthly income (for those who are single).
Applicant must present 3 years of tax statements proving the above income
http://www.thaiembassy.com/thailand/thai-permanent-residency.php