Before you start

For Social Security: legal employment in Thailand on a work permit (your employer registers you)
A Thai address and phone number for hospital registration and insurer paperwork
For private cover: budget for an annual premium and a medical history for underwriting

Step-by-step

1
Get enrolled in Social Security (employees)
When you start a job on a work permit, your employer registers you with the Social Security Office (SSO). Both you and your employer contribute about 5% of your salary each, and the employee contribution is capped (around 750 THB per month at the 15,000 THB salary ceiling).
Via employerWho: Your employer (you confirm enrolment)Within your first weeks of employment~5% of salary, capped at ~750 THB/month
2
Choose your registered SSO hospital
SSO members nominate one registered hospital where their state-covered treatment is delivered. Choose carefully — care under SSO is generally free only at that hospital. Pick one that is convenient and that you would actually be willing to use.
In personWho: YouAt enrolment; changeable yearlyFree
3
Decide on private or international insurance
Most expats add private health insurance — local Thai policies are cheaper; international policies cost more but offer wider coverage and direct billing at the top hospitals. Compare inpatient limits, outpatient cover, deductibles and whether the big private hospitals are in-network.
OnlineWho: YouA few days to compare and underwriteWide range — see totals
4
Register at a hospital and learn the system
Register as a patient at your chosen hospital (state or private) — they create a record and a hospital card. At private hospitals like Bumrungrad or Samitivej, international patient centres handle English-speaking service and can coordinate direct billing with insurers.
In personWho: You~30 min first visitFree to register; care billed per visit
5
Keep insurance documents handy
Carry your insurer's details and any cashless/direct-billing card. For visas such as the LTR or some long-stay categories, proof of health insurance can be a requirement — keep your policy certificate accessible.
Mobile appWho: YouOngoingFree

Documents you’ll need

Passport and work permit (for SSO enrolment via employer)
Social Security card / number (issued on enrolment)
Private insurance policy certificate and cashless/direct-billing card
Hospital patient card (issued on first registration)
Proof of Thai address

Things most newcomers don’t know

SSO ties you to one hospital — so expats still buy private.

Social Security covers treatment mainly at the single hospital you register with, and that hospital may not be your first choice for quality or convenience. Because of that limitation — and to access the leading private hospitals — most expats treat SSO as a baseline and carry private insurance on top.

Source: SSO / expat consensus

Bangkok's top private hospitals are excellent but pricey.

Hospitals like Bumrungrad, Samitivej and BNH draw medical tourists from around the world and offer near-Western standards with English-speaking international patient centres. The flip side is cost: without insurance, serious treatment can be very expensive, which is exactly why cover matters.

Source: Bumrungrad / International Living

Pick your SSO hospital deliberately, not by default.

Your state-covered care happens at the hospital you nominate, and quality and waiting times vary widely. Newcomers who let the choice be made for them sometimes end up registered far from home or at a hospital they would rather not use — and you can only switch once a year.

Source: SSO guidance

Local vs international insurance is a real trade-off.

Local Thai policies are markedly cheaper but may cap payouts, exclude some hospitals, and have weaker outpatient cover. International policies cost more but typically include direct billing at the flagship hospitals and broader coverage. Match the plan to where you actually want to be treated.

Source: Pacific Prime / expat guides

Common mistakes to avoid

Assuming Social Security is enough — its free care is essentially limited to your one registered hospital
Letting your employer pick your SSO hospital without checking where it is or how good it is
Walking into a top private hospital uninsured and being shocked by the bill
Buying the cheapest local policy without checking whether your preferred hospital is in-network
Forgetting that some long-stay visas (e.g. LTR) require proof of health insurance