when is a tin required 
a taxpayer identification number identifies individuals corporations and entities such as nonprofit organizations npos the tin is mandatory for anyone filing annual tax returns with the irs and the agency uses it to track taxpayers 7a taxpayer identification number is required the abbreviation tin stands for tax identification number or taxpayer identification number global tinsalmost every country uses tins for various reasons canada uses social insurance numbers sins for employment tax benefits and credit purposes 8 the sin is a nine digit unique identifier that s formatted as xxx xxx xxx countries in the european union also use tins that help government agencies identify taxpayers and allow entities to invest money across the union 9who needs a tax identification number to work in the united states or file taxes with the irs individuals need a tin a taxpayer identification number allows individuals to take advantage of benefits or services offered by the government run their day to day business operations and report their taxes 