A tax code will comprise of serieses of letters and numbers that reflect your tax free allowance and any special cases that apply on your income. For example, the number indicates how much tax-free income you’re entitled to receive, and the letter illustrates what the situation is, for example, “L” for standard allowance. If you are in BR then all your income will be taxed at the basic rate. By knowing your tax code, you know the right tax obligations, and there will be no surprises at the peak of tax season.