Hi
The SA251 exit letter is usually issued when a taxpayer's record has been automatically selected to be closed, after our systems have identified that the recipient will likely have no Self Assessment criteria in future.
It's probable that this is in response to our systems receiving the submitted return.
To confirm that the submitted return has been received, though, we would need to check your husband's record - to allow us to do this, contact us by webchat or phone via
Self Assessment: general enquiries
Thank you