OK to charge employees a varying percentage of health premiums, depending on amount of dependent coverage?

[Scott]

An employer has an insured health plan. Employees pay their portion of the premiums through a Section 125 arrangement. The employer wants to charge employees different percentages of the premiums for different coverage options. For example, assume that the total premiums are:

Employee only: $300 per month

Employee and spouse: $400 per month

Employee and dependent child: $400 per month

Employee and family: $500 per month

The employer wants to charge employees the following:

Employee only: $200 (67% of total premium)

Employee and spouse: $300 (75%)

Employee and dependent child: $200 (50%)

Employee and family: $350 (70%)

Is there any reason why this can't be done?