The decision to raise or lower the rate is made on a monthly basis by the BoE's Monetary Policy Committee (MPC).
Their decision is determined by the state of the UK economy and how they seek to influence overall borrowing in the economy. Aspects such as inflation, employment figures and consumer confidence could influence the decision to raise or lower the rate.
Once a BoE base rate change is announced, changes to our existing customer rates (where applicable) will come into effect on the 1st of the following month. If you're a Nationwide mortgage customer, we'll write to you to confirm your new rate and payment details if your current mortgage is affected.