What a local firm brings
Local firms know the register, the tax office, the local filing platform and the practice of the inspectors. They usually work in the local language and can meet in person. For a single-country business, this is usually the strongest argument, because the technical work depends on local interpretation as much as on written rules.
What an international provider brings
Cross-border providers offer one coordination point, consistent reporting formats and, in larger networks, a single engagement letter. Their value is highest where a group must consolidate several entities on one timetable, and where the client needs the same person to be responsible across jurisdictions.
The network question
Many international firms deliver foreign work through independent member firms rather than their own offices. That is a legitimate model, but it changes accountability: each member firm is responsible for its own jurisdiction, and the coordination point may not be able to compel anything. Asking which legal entity signs the engagement letter in each country resolves the ambiguity.
Hybrid arrangements
A common middle route is a local firm for domestic compliance combined with a network or group specialist for reporting, consolidation and cross-border questions. This keeps local interpretation close to the work while giving the group a single reporting channel, at the cost of an additional interface to manage.
How to decide
Count the countries where the business has real substance, not the countries where it has a registration. If there is one, a local provider is usually sufficient. If there are several with a group calendar, coordination becomes the dominant cost and a provider with coordinated coverage is usually worth the premium.
Applying this
In both models the decisive question is the same: who is accountable for a deadline in each jurisdiction, and what happens when it is missed.