During each fiscal year, we periodically assessed whether any indicators of impairment existed related to our intangible assets. As of each interim period end during each fiscal year, we concluded that a triggering event had not occurred that would more likely than not reduce the fair value of intangible assets below their carrying value.

Amortization expense related to intangible assets at our continuing operations was $0.1 million, $0.2 million and $0.3 million in 2022, 2021 and 2020, respectively. Future amortization expense for the remaining unamortized balance as of September 30, 2022 is estimated as follows, in thousands: