If you have pH above 7, then you need to do AA8.2 test. I think it's more expensive, but that's what you need to do. If your pH is below 7 and your soil is not fizzing you do standard Mehlich soil test.
"Given the ability of both the M3 and AA extractants to extract more base cations
than are actually exchangeable, which soil test can be used to extract
exchangeable cations and only exchangeable cations from a high-pH soil? The
answer turns out to be the ammonium acetate test, but only after it has been
modified to have a pH higher than the soil sample being tested.
Ammonium acetate is made by mixing aqueous ammonia NH3 with acetic acid
CH3COOH, the acid found in common vinegar. The pH of the resulting ammonium
acetate solution (NH4C2H3O2) will depend on the ratio of acetic acid to ammonia in
the mixture. If more ammonia is added the mix becomes more alkaline, more
acetic acid makes it more acidic. For soil extractant use the mixture has usually
been made at pH7 or pH7.2. Adding a pH7 solution to a soil of pH >7 will result in
alkaline mineral compounds being dissolved along with exchangeable bases. By
adding more ammonia to the solution, the pH can be raised to 8.0 to 8.5, above
the pH of most agricultural soils. For soils in the 7.0 to 8.0 pH range the
ammonium acetate extractant is commonly raised to pH8.2. This is known as the
AA8.2 soil test."
Ideal Soil by Michael Astera