present perfect: - we have already calculated the transaction costs
present simple - we calculate the transaction costs.
present continuous - we are calculating the transaction costs.
past simple - we calculated the transaction costs.
past perfect - we had already calculated the transaction costs.
past continuous - we were calculating the transaction costs.
future simple - we will calculate the transaction costs.
future perfect - we will have already calculated the transaction costs.
future continuous - we will be calculating the transaction costs.