The calculation is as follows: $600 x 52 (#of weeks in a year) divided by 12 (months). This monthly amount would be $2600 x 70% - Her base benefit would be $1820 per month. Be sure to check the policy if her benefit would reduce by any other income such as retirement or social security. If so, the benefit would be less. The intention is that she would receiving about 70% of her income from all income sources combined.