If you have had a transfer of undertakings (protection of employment) (TUPE) transfer or have combined multiple pension accounts, this date reflects the most recent contract start date and not your original date of joining.
Your annual benefit statement may show a later starting date than you would expect to see, this may be because we are currently working on aggregating (joining) more than one pension record together, following a change in post or contract. You will be informed as soon as this has been done and you can then check your continuous period of service on your record through the Portal and run an additional benefit calculation if you wish to.