Black Hills WorksEIN #46-0341382 2021 Tax Return (IRS 990) 2020 Tax Return (IRS 990) 2019 Tax Return (IRS 990) Black Hills Works IRS Determination Letter Black Hills Works Foundation EIN #46-0363653 2022 Tax Return (IRS 990) 2021 Tax Return (IRS 990) 2020 Tax Return (IRS 990) 2019 Tax Return (IRS 990) 2018 Tax Return (IRS 990) 2017 Tax Return (IRS 990) 2016 Tax Return (IRS 990) Black Hills Works Foundation IRS Determination Letter