According to the Prudence concept, revenues should not be recognized until it is certain that it will result in inflow of economic benefits such as cash or kind to the entity.
Similarly, expenses should be recognized immediately until it is uncertain (< 50%) that it will result in outflow of economic benefits such as cash or kind to the entity.
Revenues and expenses should be recognized in same in which is incurred rather than when cash is received or paid.
According to the Matching concept, revenue and expense should be matched. It is because expenses are incurred with a view to earn revenue. Therefore, revenue earned by the entity should be included in the same period when expense is incurred.