Medical providers in Singapore are not required to accept insurers' Letters of Guarantee or insurers' other representations about bill payments. As a courtesy they often do, and the public restructured hospitals are on average more relaxed in this way, but it's at their sole discretion.
Medical providers are more likely to demand immediate bill payment in these circumstances (notable examples):
1. The medical procedure is not medically necessary. Integrated Shield plans all have a medical necessity provision and won't pay claims otherwise.
2. The medical provider is concerned the patient has reached, or will soon reach, a policy limit such as an annual limit.
3. The medical provider fears that a claim will be denied due to a preexisting condition exclusion, with reimbursement only at the MediShield Life level.
4. The provider has/had a past payment collection issue with the same patient or his/her immediate family.
5. The patient is unsubsidized (didn't get a polyclinic or public hospital A&E referral).
6. The patient wants to stay in a high (expensive) ward class.
7. The patient is not a Singaporean citizen.
8. The patient is not a Singapore Permanent Resident.
9. There's a high rate of complications and/or long hospital recuperation period.
10. The care is related to some other coverage exclusion, such as self-harm (suicide attempt, substance abuse, etc. -- although this may change at least for MediShield Life coverage in 2021), certain HIV transmission paths, "avoidable" COVID-19, and some other examples.
11. The patient abused the provider's staff in a previous encounter.
