Not necessarily. In most cases, you can have a billing entity based on a different country, though the billing region associated to its payment method should match the benefits region. That is, if you're offering benefits for your employees in the UK, your billing entity might be based in another country, but it should be billable in GBP. The same thing for any benefits offered in EU countries: regardless of the billing entity country, it should be billable in EUR currency.
However, for certain benefits, you need to have a legal entity in the same country - see below.
Irish benefits (Health, Pension and Life Assurance) require an Irish Tax Registration Number (TRN) - though your billing entity might be based in other country than Ireland
UK Health does require a UK billing entity
If you have a specific question about your billing region, please contact us.