If you experience non-service connected illness/ injuries post deployment you may be charged a co-pay for treatment of these conditions. For example: flu, colds, auto accident, etc.

If treatment is provided that is clearly unrelated to your service in the theater of combat operations (e.g. auto accident, common flu, broken limb) you may be assessed a co-pay for such treatment (if you have no other qualifying eligibility criteria).

More info here: VA Health Care