Click on Verify Authenticity of Registration : To verify already registered with the Inland Revenue Department
tick "Verify Registration" (first button)
https://www.ird.gov.lk/en/eservices/sitepages/access to e-services.aspx?menuid=1803
he/She has a tin ..... (from my experiance)...
If you carry on as a business, certain expense are allowed to deduct as expenses (from income) ... But if you are carrying on as personal freelance , your total income is taxed ...
there are certain benefits on "business tax"