Upgrading a DB instance for Amazon RDS Custom for SQL Server
You can upgrade an Amazon RDS Custom for SQL Server DB instance by modifying it to use a new DB engine version, the same as you do for Amazon RDS.
The same limitations for upgrading an RDS Custom for SQL Server DB instance apply as for modifying an RDS Custom for SQL Server DB instance in general. For more information, see Modifying an RDS Custom for SQL Server DB instance.
For general information about upgrading DB instances, see Upgrading a DB instance engine version.