I want to know how to calculate the tax rate of 3.67% for small-scale taxpayers in service industry.

3.67% is the comprehensive collection rate. Including:

Business tax: operating income ×3%

Urban construction tax: business tax ×7% (or 5%, 1%)

Education surcharge: business tax ×3%

Local education surcharge: business tax ×2%

The above comprehensive tax rate is: 3%+3%×(7%+3%+2%)=3.36%

Individual (enterprise) income tax: operating income × approved collection rate, which varies from place to place.

Additional in other places: operating income × collection rate. There are different names and collection rates in different places.

You can add up the taxes (fees) of the corresponding items from the tax stamps printed for you and divide them by the operating income to get the collection rate of 3.67%.