The Home Office are on the look-out for sudden increases to salaries where these neatly satisfy ILR requirements.
The minimum salary requirement for ILR is currently £35,500 p.a., and this increases again in April to £35,800 p.a. Some employers, whose staff fall under this limit, increase salaries just in time to satisfy the ILR requirement, but the Home Office are now looking more closely at these increases. They may ask to see appraisal records to show how salaries are reviewed and any criteria applied to justify such increases.
So if you employ staff whose salaries fall well under the £35,800 limit, you may wish to consider increasing these in stages over time to avoid these questions being asked. Needless to say, any increases must be appropriate to the work the sponsored worker is carrying out.