Form 12BB is the declaration you submit to your employer, usually toward the start of the financial year and again before it ends, listing the tax-saving investments and expenses you intend to claim — HRA, LTA, home loan interest, and Section 80C investments among them.
Your employer uses this declaration to estimate your tax liability for the year and deduct the correct amount of TDS from your monthly salary accordingly. If you declare investments you don't actually end up making, or overstate your HRA claim, your employer's TDS calculation will be too low, and you'll owe the difference — sometimes as a lump sum — when you actually file your return.
This is why many employees see a noticeably smaller salary in the last month or two of the financial year: it's often the point where employers ask for actual proof of the investments declared in Form 12BB, and adjust the remaining TDS if the proof doesn't match the earlier declaration.
Submitting Form 12BB honestly, based on what you're actually confident you'll invest or spend, avoids both an unpleasant surprise at year-end and the hassle of a larger-than-expected tax payment when filing.
Frequently asked questions
What is a salary calculator with old vs new regime comparison?
It takes your gross annual salary and computes your income tax liability under both the old and new tax regimes side by side, factoring in standard deduction, applicable slabs, cess, and rebates, so you can see which regime results in lower tax for your specific numbers.
What is the key difference between the old and new tax regimes?
The old regime has fewer, wider slabs but allows numerous deductions and exemptions like 80C, HRA, and home loan interest, while the new regime offers lower slab rates and a larger tax-free threshold but removes almost all deductions except the standard deduction.
Which regime is the default now?
The new tax regime is the default option for all taxpayers; if you want to be taxed under the old regime with its deductions, you must explicitly opt for it, either when filing your return or by informing your employer for TDS purposes.