Updated : 26/10/2017
First, check that your national health system or insurance covers the planned treatment. Then, you can decide how you want the costs of treatment to be covered.
Option 1 - prior authorisation
You will be reimbursed according to the conditions and reimbursement rates in the country where the treatment takes place. If you choose this option, you can access publicly provided healthcare, and you'll need to apply to your national health insurance body for prior authorisation (form S2) to go abroad for treatment.
If you have a right under national law to the treatment you're applying for, but it can't be provided within a medically reasonable time, authorisation must be granted. If you're not automatically entitled to the treatment, however, your national health insurance body may decide to refuse authorisation.
If you've obtained form S2, your treatment costs will be reimbursed according to the rules in the country where you're treated. This will be dealt with by the relevant institutions in your home country and the country of treatment, so as a rule you will not have to pay upfront.
Option 2 - claim reimbursement after treatment
You can opt to pay upfront for your treatment and claim reimbursement later according to the reimbursement rates applied for the same treatment in the country where you're insured. If you're insured in a country that doesn't use reimbursement, then there will be a tariff indicating the cost of that treatment to the system. It doesn't matter whether the hospital or clinic where you'll be treated is public or private.
In some limited cases you may have to apply for prior authorisation - check this with your health insurance body or National Contact Point. Again, your application must be granted if you would otherwise have to wait too long for treatment at home.
The cost of your treatment abroad is covered only if the national social security system in the country where you're insured covers it. If it doesn't, your national health insurance body is not obliged to authorise treatment abroad or to reimburse the costs (although, of course, it may choose to do so).
Contact your national authorities to find out what options are available to you.