I agree, small and overworked accounting firms (or any other service business) will eventually result in bad service too, even though it’s unintentional.
To me, boutique is not just about number of employees but also about approach to business.
Google defines boutique as “a business that serves a sophisticated or specialized clientele.”
In our case, before deciding on where to move, we did some research and planning. We were in the process of doing some tax and estate planning so we thought we would use that as an opportunity to interview different accountants.
We identified potential accounting firms and sent them emails (with a brief) to request (paid) appointments. We used this time to discuss our frustrations with the previous firms (situations we wanted to avoid) as well as strategic issues we were considering at the time, asking for advice.
We eventually moved to a boutique firm, specialising in owner operated/managed businesses. Things that stood out during the initial discussion include the accountant’s approach to billing (transparent and willing to work on retainer or per hour), approach to work in general (only works from the office in mornings and then remote for rest of the day), as well as time spent working at large firms in the states. The international exposure, although not immediately critical, is useful in terms of our business’ ambitions.