An HRA (House Rent Allowance) calculator is an online tax planning tool that helps salaried employees in India compute the tax-exempt portion of their HRA — determining how much of the HRA component of their salary is eligible for income tax deduction under Section 10(13A) of the Income Tax Act. The exempt HRA is the minimum of three amounts: the actual HRA received, 50% of basic salary (for employees in metro cities — Delhi, Mumbai, Chennai, Kolkata) or 40% (for non-metro cities), and the actual rent paid minus 10% of basic salary. The HRA calculator automates this three-way comparison, taking inputs of the monthly HRA received, basic salary, rent paid, and city of residence to compute the exact tax-exempt amount and the taxable HRA balance. Accurate HRA exemption computation is essential for employees filing their income tax returns and for submitting correct tax savings declarations to their employers for TDS purposes — over-claiming HRA exemption can trigger income tax notices, while under-claiming results in unnecessary tax payment. The HRA calculator is particularly useful during the annual investment declaration season (typically January to March) when employers require employees to submit rent receipts and landlord details for HRA above ₹1 lakh per annum in rent payments.