FLR(M) time out of country

What a fantastic resource this is! I’ve silently lurked for years and you all have helped me successfully apply for 2 visas so far, so thank you! I’m married to UK citizen and granted FLR(m) last year. My BRP expires in November 2023. Is there a limit of how long I can remain outside the country with my spouse before my visa is no longer valid and I must re-apply/start the whole process over again if I don’t yet have ILR? I see a 120 day rule referenced to qualifying for ILR. Is it best to use that as a gauge? I ask since my husband has been offered an international work contract that could last 9-12months.

Welcome to UKY!

Your spouse visa will continue to be valid for as long as it is stated, so it will continue to be valid until November 2023. It's not like ILR where if you're outside the UK for X amount of time, it will be cancelled and you'll have to start from scratch again.

In regards to days spent outside the UK before applying for ILR, while other immigration paths have defined limits on time spent outside the UK (no more than 180 days in 12 months), this limit does not apply to spouse/partner visas.

That being said, you should still be mindful of how much time is spent outside the UK, and whether you remain living together or apart during these times. To qualify for ILR, you need to demonstrate that you've been maintaining your relationship (e.g., living together), intend to live permanently in the UK, and have lived in the UK for the qualifying time (5 years) prior to application.

E-LTRP.1.10. The applicant and their partner must intend to live together permanently in the UK and, in any application for further leave to remain as a partner (except where the applicant is in the UK as a fiancé(e) or proposed civil partner) and in any application for indefinite leave to remain as a partner, the applicant must provide evidence that, since entry clearance as a partner was granted under paragraph D-ECP1.1. or since the last grant of limited leave to remain as a partner, the applicant and their partner have lived together in the UK or there is good reason, consistent with a continuing intention to live together permanently in the UK, for any period in which they have not done so.

E-ILRP.1.3. (1) Subject to subparagraph (2), the applicant must, at the date of application, have completed a period of continuous residence in the UK of at least 5 years (60 months)

https://www.gov.uk/guidance/immigration-rules/immigration-rules-appendix-fm-family-members

The guidance on family policy highlights this:

If the applicant, their partner or both have spent the majority of the period overseas, there may be reason to doubt that the couple intend to live together permanently in the UK.

But also:

Good reasons could include time spent overseas in connection with the applicant’s or their partner’s work, holidays, training or study.

https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/1083448/Family_life__as_a_partner_or_parent__and_exceptional_circumstances.pdf

(note, all bold emphasis is mine)

Now, all that being said, if you will live with your partner outside the UK, and it is a temporary work assignment for about a year or less, I don't see a huge issue applying for ILR. Just explain the reason why you've lived outside the UK and provide evidence in your application, and ensure your current visa doesn't expire while you're outside the UK.