ILR (Set M) - When to Apply?

Hello,

My wife will be applying for indefinite leave to remain (SET M) in 2021.

I wonder if someone could please clarify when we should apply - 28 days before her 60 months in the UK from date of entry is completed or 28 days before the expiry date on her second (i.e. further leave to remain) BRP? The reason I ask is that there is quite a gap between these two dates and I dare not risk either applying too early or too late.

The key dates are:

Date of issue of entry clearance: 12/02/2016
Date of entry: 19/02/2016
60 months in UK from date of entry: 19/02/2021
60 months in UK from date of entry minus 28 days: 22/01/2021
BRP expiry: 13/05/2021
BRP expiry minus 28 days: 15/04/2021

Thanks in advance

Earliest she can apply is when she completes 60 months minus 28 days from the date of first entry in UK. The latest she can apply is anytime before current visa expiry.

Great - many thanks for advising so quickly - much appreciated