If your salary is not updated by your employer when beginning a new role, employers should legally be required to backdate your pay once the new salary comes into affect.
Why is this important?
Speaking with friends and family, this is not an unusual practice for employers to promote staff and not action the agreed salary until sometime after. Employees in the meantime are being underpaid for their new role. Making this a legal requirement will ensure that employers are more proactive and fair when promoting staff.