Why onerous contracts are considered as a provision, even though they do not always come with a high probability of being an obligation?

A contract is assigned on 31st March, 2015 to render the bookkeeping service to company A before the end of June 2016. The agreed price is $120. according to the agreement, if the service is not rendered by end of June, 2016, then you should pay company A the penalty of $100. At the end of June 2015, you find that the minimum cost incurred to render the service is increased to $150.

• Recording at the end of 2015 and 2016?

• What if the penalty is $10?