For Voluntary NI contributions, in relation to UK state pension it is perhaps mainly useful for the year 2016-2017 or later..
I have had a contracted out pension mostly, and was contracted in from about 2015, 40 years solid NI record but need another 6 years NI to get the current max state pension, voluntary contributions quoted as circa £830 per year, which still could be a good deal BUT only if the .Gov does not move the goal posts again. I qualified for full state pension in 2010 (30yearsNI) goal-post move in 2015 again but almost instantly qualified for max state pension ( 35 years NI). System change in 2016 leaves me with 6 years Short! May do 3 years Voluntary (if pro-rata, will have to check), but Think anything else will go in the private pension...Hopefully may return to work this year, and get the other 3 years paid that way.
The UK Gov is still pushing the line, "we are all living longer" which is nonsense now, if anything the trend has reversed now. One of the biggest drivers of the trend was movement from heavy industry to light in past decades, which is largely over. With unexplained (as yet) excess deaths, COV, cost of living crisis (heating/food quality) seems implausible that life expectancy is still going up in the UK and similar,
The Son never got Child benefit in Thailand for 0-13years, even though I was always working fulltime and paying NI in the UK (Days in Lieu and holidays, always in Thailand). Payout was based around the political hobby, rather than being run as insurance. Now in the UK, with the Son doing High school, and found they, some time ago, withdrew the NI credits that used to go with the Child Benefit, for kids over over 12years. (never lucky).
Sorry if a bit negative...Happy New Year! ????????