The Scottish Government wants around one million tonnes of residual waste and recyclable materials to stop being buried in the ground.
However less than half of Scotland’s 32 councils have plans to meet the 2021 target.
This ban on sending waste to landfill sites in Scotland is set to hit the country’s economy with a cost of £1 billion due to the price of exporting waste to England and increasing recycling capabilities.
From January 2021, Scottish landfill operators will be banned from accepting biodegradable municipal waste for disposal in landfill.
The report, commissioned by Scottish ministers, said: “Excluding consideration of waste minimisation and recycling, the ban will result in significant economic costs to Scotland due to the need to export an increased amount of residual waste – whether as an interim solution until new thermal treatment capacity comes online, or as a long-term solution.”
Scottish Liberal Democrat leader Willie Rennie said: “It would make a mockery of the law if the SNP’s solution to meeting their own landfill ban is to ship it to England or abroad.
“Ministers are relying on a loophole so big you could drive a rubbish truck through it.”
The Scottish Environmental Services has warned against brining in the landfill ban on biodegradable municipal waste too early as it says the country does not have sufficient non-landfill treatment capabilities available to deal with the extra material.