The difference between a regular Plan G plan and a High Deductible Plan G plan is the deductible amount and coverage timing. With a standard Supplement Plan G, you’re covered immediately and are responsible only for the $233 Part B deductible, plus your monthly premium. With a high-deductible Plan G, your coverage begins once you pay your $2,490 deductible, which then covers all future out-of-pocket costs.  Determining which one is best for you depends on your situation and if you need the coverage Plan G provides immediately or if it makes more sense to pay the lower premiums until that higher deductible is met.