How does ILR 180 days Absence calculation works

[anantcs08]

Please help as I am confused about 180 days absence calculation considering future ILR application.
How does ILR 180 days calculation work ?
Was out from UK continuously for 137 days this year from 5th July 2020 to 18th November 2020, first ever entry in UK was on 1st October 2018.
I didn't had any other leave in 2020 , last time I was out from UK in October 2019 for 20 days.

I have my wedding planned in April 2021, For how long can I go out from UK next year without creating problems in my future ILR application ?

Thanks

[CULLINAN]

What is your visa category?

[anantcs08]

I am on general Tier 2 Visa issued on 09-September-2018 and I entered UK first time on 1st October 2018.

[CULLINAN]

I am on general Tier 2 Visa issued on 09-September-2018 and I entered UK first time on 1st October 2018.

You should not be outside UK for more than 180 days on rolling basis i.e. ANY 12 months. Calculate accordingly.

[anantcs08]

"rolling basis i.e. ANY 12 months" that part I doesn't understand does calculation start from visa received date or a exit from UK .

[CR001]

It is any period of 12 months at any time.

[CULLINAN]

Also see:
https://assets.publishing.service.gov.u ... gov-uk.pdf

[CULLINAN]

For example:

1/1/2019 - 31/12/2019 (no more than 180 days)
2/1/2019 - 1/1/2020 (same as above)
3/1/2019 - 2/1/2020 (same as above)
etc

and so on.