Form 1098 Mortgage Interest Calculator

Estimate what will appear on your Form 1098 before your lender mails it. Covers Box 1 interest, points deductibility rules, TCJA deduction limits, and the itemized vs standard deduction decision.

$
%
yrs
$
$
$
Estimated Form 1098 — Box 1 Interest
$23,511
Mortgage interest paid in year 1 of your loan
Box 1: Interest Paid
$23,511
Box 2: Outstanding Principal
$350,000
Box 5: MIP / PMI
$0
Box 6: Points Paid
$0

Your Form 1098 has up to 11 boxes. Here is what each one means and how it is used on your tax return.

Box 1 — Mortgage Interest Received
$23,511
The main number. Total interest paid to your lender in the calendar year. Goes on Schedule A, Line 8a.
Box 2 — Outstanding Mortgage Principal
$350,000
Balance at the start of the calendar year. Used to verify the $750K/$1M cap applies. Not itself a deduction.
Box 3 — Origination Date
Date only
The date your mortgage was originated. Loans before Dec 16, 2017 have a $1M cap; newer loans are capped at $750K (TCJA).
Box 4 — Refund of Overpaid Interest
$0
Rare — if lender refunded you interest from a prior year. Reduces your deduction.
Box 5 — MIP / PMI
$0
Mortgage insurance premiums. May be deductible depending on income phase-out rules.
Box 6 — Points Paid on Purchase
$0
Points paid at origination. Purchase loans: deduct in full year paid. Refi: must amortize.
Boxes 7–11 — Property Address
Identification only
Used to match your 1098 to the correct property. No tax calculation.
Deductible Mortgage Interest
$23,511
TCJA loan — $750,000 cap applies (originated Dec 16, 2017 or later)
Loan Origination
2020
Post-TCJA — $750K cap
Deduction Cap
$750,000
Maximum loan amount for interest deduction
Your Loan Balance
$350,000
Under cap — full deduction
Deductible Interest
$23,511
Interest eligible for Schedule A
TCJA rule (since Dec 16, 2017): If your loan exceeds the cap, only the proportional interest is deductible. Example: $900K loan with $750K cap means 750/900 = 83.3% of your interest is deductible. The $1M limit is grandfathered for loans originated before December 16, 2017 and not refinanced for a higher balance.

How to Use This Form 1098 Calculator

Enter your original loan balance, interest rate, and loan term. Select which year of the loan you are filing taxes for. The calculator estimates what you should expect to see on Box 1 (mortgage interest paid), Box 2 (outstanding principal), Box 5 (MIP/PMI), and Box 6 (points paid) of your Form 1098.

This calculator is for estimating your 1098 values for planning purposes. For actual tax filing, always use the Form 1098 mailed by your lender by January 31.

What Is Form 1098?

Form 1098 is the Mortgage Interest Statement issued by your lender each January. It reports the interest you paid on your mortgage during the prior calendar year. Lenders must issue a Form 1098 if you paid $600 or more in mortgage interest.

Box 1: Mortgage interest received (main deduction figure)
Box 2: Outstanding mortgage principal (Jan 1 balance)
Box 3: Mortgage origination date
Box 4: Refund of overpaid interest
Box 5: Mortgage insurance premiums (MIP/PMI)
Box 6: Points paid on purchase of principal residence

Example: Reading a Form 1098

Sarah — First Year of $400,000 Mortgage at 7%

Original Loan$400,000
Interest Rate7.00%
Box 1: Interest Paid (Year 1)$27,892
Box 2: Outstanding Principal (Jan 1)$400,000
Box 6: Points Paid at Closing (1 point)$4,000
Property Tax Paid (Box 4 or county bill)$5,200
Total Itemized (Interest + SALT + Charity)$37,092
Standard Deduction (MFJ 2025)$29,200
Additional Itemized Benefit$7,892

Sarah and her spouse itemize because their combined deductions exceed the standard deduction by nearly $8,000.

Frequently Asked Questions

Lenders must mail Form 1098 by January 31 each year for the prior tax year. Most lenders also make it available electronically through your online account, often available in early January. If you have not received it by mid-February, contact your lender or servicer directly.
No. Points paid on a refinance must be amortized (deducted ratably) over the life of the new loan. If you have a 30-year refinance and paid $3,000 in points, you can deduct $100 per year. Points on an original purchase mortgage are generally deductible in full in the year paid, provided IRS requirements are met.
Under the Tax Cuts and Jobs Act (TCJA), interest on mortgages originated on or after December 16, 2017 is deductible only on up to $750,000 of loan principal. Mortgages originated before that date are grandfathered at the prior $1,000,000 cap. If your loan exceeds the cap, only the proportional interest is deductible.
The mortgage insurance premium (MIP/PMI) deduction has expired and been reinstated several times by Congress. Check current IRS guidance for the applicable tax year. When available, it phases out for AGI above $100,000 for single filers and $50,000 for married filing separately.
You should itemize only if your total itemized deductions (mortgage interest + SALT capped at $10,000 + charitable contributions + other) exceed the standard deduction ($14,600 single / $29,200 married filing jointly for 2025). With high interest rates, many homeowners can benefit from itemizing, especially in the early years when interest payments are highest.

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