Is there supplemental disability insurance

Yes, and it's recommended to add supplemental disability insurance to cover closer to 100% of your income.

If you have disability insurance through your employer, your benefit will be capped at 66% of your income. The benefit received from a group disability policy (through your employer) is taxable.

Supplemental disability insurance benefits are not taxable. You can add Catastrophic rider on an individual disability insurance policy, to cover up to 100% of your income in combination with your existing employer group DI.