Box 14 on a W-2 is an Informational Box by: Vickey
Since Box 14 is simply an informational box for the taxpayer...there is no special code you need to put in for reporting the housing allowance payments.
I put HA: $15,000.00 (for example) ...so the minister will know what that amount reported in Box 14 is...but you could also type out the whole thing such as "Housing Allowance", Clergy Cash Housing", etc.