So, once the normal working hours are ascertained, the calculation of a week's pay is possible. First, if the employee's remuneration does not vary with the amount of work done, then the week's pay is the amount payable by the employer under the contract of employment in force on a particular "calculation date" (which varies slightly according to whether the claim is for a guarantee pay or redundancy pay, etc.) if the employee were working his normal weekly hours. So for a normal 40-hour week at £2-50 an hour, or £100 a week, or £5,200 a year, there is obviously no difficulty as to the week's pay. If the remuneration does vary according to output, for example, by productivity bonus or commission, the amount of the week's pay is discovered by looking at the previous 12-week period, adding up the weekly payments actually received during that time and dividing by 12.