How Tier 2 5 years is calculated for ILR?

I started working with Tier 2 General visa from August 2018 and noticed on my first BRP it is mentioned the issue data in 16-10-2018 valid until 14-08-2019. I extended my Visa next year in July and received the BRP with Valid date from 11-07-2019 to 2021-08-14
My question Is in my first BRP my tier 2 visa length is less than 1 year and for my second visa it is more than 2 years. Why all my BRP ended in 14-08-xxxx
Also I lost my Tier 2 2 month ago and applied for a new Tier 2 application for 3 years now. (I applied in August) My main question is given these timeline, does my Tier 2 number of years starts from valid date of my first BRP card which is in October even if I started working from August with valid Tier 4 visa (3 months extra after finishing my masters) and in that case I need new Tier 2 visa for only 1 month to cover 5 years or I can apply for ILR in 60 days remained after finishing date in my currently BRP which is 14-08-2023

A tier 2 visa is only granted based on the length stated in the cos.

Your ilr qualifying period starts from the date your tier 2 is valid and NOT the date you started working for your sponsor while still on a tier 4 visa.

Thank you for your answer. I can see there is a difference between my COS start and end date and the valid date and end date mentioned in my BRP. Just to make sure, the date written in the COS is considered for 5 years tier 2 employement for ILR right?

I can see there is a difference between my COS start and end date and the valid date and end date mentioned in my BRP.

What is the difference in dates? What dates and length of duration was stated in your original cos?

Just to make sure, the date written in the COS is considered for 5 years tier 2 employement for ILR right?

No. It is the date your tier 2 brp is valid from that is used for ilr.

In my COS, start date is 01-08-2018 and end date is 31-07-2019 which is when I worked in reality as well. I applied with standard time(no priority) so I received my BRP after around 2 months and the valid BRP date is from 16-10-2018 until 14-08-2019 (notice the end date matched the end date +14 days in my COS but not the start date of validation in BRP. Do you think this makes me eligible to apply for ILR in 28 days befor 01-08-2023?

A visa is only valid form the date is is approved and not before.

Your ilr qualifying period starts from your tier 2 visa start date, ie the 16th October.

Your cos start date is completely irrelevant. A cos is NOT a visa.

I just found this https://assets.publishing.service.gov.u ... pdf#page11

Is this change anything?

What about the document or should I try guess what specifically you are referring to?

the link will bring you to the location which indicates how 5 years is calculated. It is not a general link to a document!

The link takes me to page one of the document.

What specifically are you referring to in the actual document?? I am fully aware of the document and what it is, but you are not being clear in what you are referring to.

This is what is written in page 11 of Indefinite leave to remain: calculating continuous period in UK document available at the link:

Calculating the specified continuous period
Applicants can submit a settlement application up to 28 days before they would reach the end of the specified period.
You must calculate the relevant qualifying period by counting backward from whichever of the following is most beneficial to the applicant:
• the date of application
• the date of decision
• any date up to 28 days after the date of application
UK Ancestry applicants have different requirements covering application dates, see: UK Ancestry.

I can see I submitted my application sometime in July 2018 and posted my document in 02-18-2018. Does that mean that make me eligible to apply for ILR 28 days before 01-08-2023?

No, it does not mean your initial tier 2 application date is the relevant date.

That applies to ilr for caseworkers and not the initial tier 2 application date. It does very clearly say :

Applicants can submit a settlement application up to 28 days before they would reach the end of the specified period.
You must calculate the relevant qualifying period by counting backward from

Yes it is clearly mentions that! My bad!