How will my subsidy balance be calculated for my existing CHAS Chronic Tier and the new Healthier SG Chronic Tier, if I alternate between them for different visits?

Your remaining dollar-based subsidy balance will be pro-rated accordingly for each visit, depending on the subsidy tier that you choose to use for the visit. You may wish to consult your Healthier SG clinic/doctor about switching between the existing CHAS Chronic Tier and the new Healthier SG Chronic Tier, depending on your medication needs.
If your dollar-based limits under the existing CHAS Chronic Tier are exhausted, that would mean that your dollar-based limits under the new Healthier SG Chronic Tier would have been exhausted as well.
However, you will still be able to receive the percentage-based subsidies for selected chronic medications under the new Healthier SG Chronic Tier, as there is no cap to those subsidies.
Healthier SG benefits and subsidies are available/accessible at your enrolled Healthier SG clinic.