The closure of Thoresby and Kellingley Collieries could cost the taxpayer up to £75 million, according to the TUC.
UK Coal plans to close the two deep mines by the end of 2015 and has done a £20 million deal with the government to avoid insolvency.
This means more than 500 jobs will go at the Nottinghamshire pit and a further 80 people from the county will be affected, as their jobs were moved to the Kellingley mine in North Yorkshire after the closure of Welbeck and Daw Mill Collieries.
The Trades Union Congress, which is fighting the closures, claims the loss of income tax and the large costs of unemployment, such as the additional claims in benefits, will mean the taxpayer foots a larger bill.
Instead it has called on the government to apply for between £63 million and £74 million of state aid from the European Union to keep the pits open, saying it could "easily be covered" by an estimated £86 million of extra profits generated between 2015 and 2018 from over £500 million in coal revenues.
TUC General Secretary Frances O'Grady, said: "Recent events in the Ukraine should have made clear the importance of having a secure domestic energy supply.
"Instead the government is allowing two of Britain's three remaining coal mines to close, causing the unnecessary loss of 1,300 skilled jobs and leaving us even more exposed to fluctuations in the price of imported coal.
"But British coal mining does have a future if the government wants it to. An application for state aid would be cost neutral, save jobs and help ensure that UK mined coal supports our emerging CCS industry. The profits from extra coal production would save the taxpayer money too.
"With thousands of jobs and the UK's energy security at stake, ministers must put aside their reluctance to intervene and apply for EU state aid. It would madness to allow the closure of British mines when countries like Germany and Spain are using far greater amounts of state aid to bolster their own domestic coal supply."
But UK Coal still believes the managed closure deal with the government was the only way to avoid insolvency and immediate closure.
