Your employer decides your contribution rate based on how much you earn. If you have more than one job, your contribution rate will be decided separately for each job. Your contribution rate will be re-assessed every April. If your pay changes during the year, your employer may decide to review your contribution rate at that time. The pay bands are adjusted each year in line with inflation.
The calculator assumes you are resident in Scotland for tax purposes. It does not accurately reflect tax relief for employees earning over £100,000 (where the tax allowance reduces by £1 for every £2 earned over £100,000).