A report from a national watchdog group says a cut to the tax that coal companies pay to fund a trust for sick miners will cost taxpayers billions of dollars. The Washington-based group Taxpayers for Common Sense released a report that says the Black Lung Disability Trust Fund’s debt could be at least $15 billion by 2050. The excise tax on mined coal expired at the beginning of 2019 due to inaction by Congress. That led to a reduction in the amount coal companies pay into the fund. The fund pays benefits and medical bills for miners diagnosed with black lung disease.