Tcs u/s 206(1H) for ST individual

My client is an ST individual, income exempted u/s 10(26) and running a petrol pump located in tribal areas. TCS is applicable for his purchases. his seller is asking for TCS exemption certificate. I understand that Form 13 cannot be applied in this case neither Form 27c is applicable.

Can my client apply for TCS exemption under 206(1c) on ccount that his income is exempted u/s 10(26)?

thanks a lot for your advice!