A tense used to express an ongoing action completed after some time in the future. In English it is formed by use of will have been (or shall have been) and a present participle
Example: By the end of this year, I will have been working here for 10 years.
{i} verb tense that describes an action that has not yet been completed and will be finished in the future (e.g., "By that time, I will have finished")