The reimbursement scheme: why it was introduced
When claims for repayment of overpaid excise duty are made, we are entitled to refuse repayment if the claimant would be unjustly enriched. Broadly speaking this is where a claimant would get a windfall profit. This is because the consumer effectively paid the excise duty that they are seeking to recover, and the claimant is not planning to pass the repayment back to the consumer.
Until 1997 a revenue trader who accepted that they would be unjustly enriched would still receive a repayment under CEMA section 137A so long as they agreed to reimburse those consumers who for all practical purposes had paid all or part of the duty.
However the law did not say how that refund should be made, nor did it provide for sanctions when a revenue trader reneged on the agreement. This situation changed with the introduction of the reimbursement scheme.