In assessment, self-assessment is 

Self assessment takes place when the student assesses his work and uses his feedback to rectify the errors and move ahead. Key Points

• In this assessment, learners are asked to assess their performance on their own, they use various assessment techniques and strategies to assess themselves.
• This practice helps learners to identify their knowledge gaps, adopt appropriate learning strategies and use assessment as a tool for new learning.
• It encourages students to take responsibility for their own learning. It requires students to ask questions about their learning.
• It encourages peer assessment, self-assessment, and reflection.

​Hence In assessment, self-assessment is assessment as learning.