These letters are going to employers who HMRC considers may have claimed more CJRS grant than they are entitled to and/or may not meet the conditions to receive a CJRS grant.
Many employers have found the evolving CJRS rules difficult to follow. In some cases this will have led to innocent errors, particularly in relation to claims for the earlier furlough periods. It may be that any query over entitlement relates to a genuine error or mistake, but even where grant has been claimed in error it will need to be paid back. There are also time limits within which directors must declare any overpayments to HMRC once they become aware of them. For more information on this please see our June briefing Coronavirus Job Retention Scheme risks: Government announces clawback regime.
If you receive a letter like this please get in touch with your usual Osborne Clarke contact. Our tax investigations lawyers are experts in this area and can advise you accordingly.