Mortgage Interest Deduction
Deduct interest on your home loan - one of the largest tax breaks available
💰 Quick Overview
- ✓ Deduct interest on up to $750,000 of mortgage debt (loans after 12/15/2017)
- ✓ $1 million limit for mortgages before 12/16/2017 (grandfathered)
- ✓ Must itemize deductions (total > $22,500 HOH standard deduction)
- ✓ Applies to your primary residence and one second home
- ✓ Home equity loan interest only if used to "buy, build, or substantially improve" home
Is It Worth Itemizing?
You can only deduct mortgage interest if you itemize. Compare total itemized deductions to $22,500 HOH standard deduction:
Worth Itemizing ✓
- Mortgage interest: $14,000
- Property + state tax: $10,000 (SALT cap)
- Charitable: $3,000
- Total itemized: $27,000
- Benefit: $27k - $22.5k = $4,500
- Tax savings: $4,500 × 24% = $1,080
Standard Better ✗
- Mortgage interest: $8,000
- Property + state tax: $10,000
- Charitable: $1,000
- Total itemized: $19,000
- Standard deduction: $22,500
- Take standard - save $3,500 more
Mortgage Debt Limits
| Mortgage Taken Out | Debt Limit | Details |
|---|---|---|
| Before 10/13/1987 | Unlimited | All interest deductible |
| 10/13/1987 - 12/15/2017 | $1,000,000 | Grandfathered limit |
| After 12/15/2017 | $750,000 | Current law (TCJA) |
Note: If you refinance a grandfathered loan, you keep the $1M limit as long as new loan doesn't exceed original amount.
Real Examples
Example 1: New $500k Mortgage
- Purchase price: $550,000 (2024)
- Down payment: $50,000
- Mortgage: $500,000
- Interest rate: 6.5%
- Year 1 interest paid: ~$32,000
- Under $750k limit: ✓ All $32,000 deductible
- Other itemized: SALT $10k + charity $2k = $12k
- Total itemized: $44,000 vs $22,500 standard
- Extra deduction: $21,500 × 24% = $5,160 saved
Example 2: $1.2M Mortgage (Exceeds Limit)
- Mortgage: $1,200,000 (purchased 2023)
- Interest rate: 7%
- Total interest paid: $84,000
- Deductible portion: $84,000 × ($750k/$1.2M) = $52,500 only
- Non-deductible: $31,500 (above $750k limit)
- ⚠️ Must calculate percentage: (Limit / Loan Amount) × Interest
Example 3: Refinance Grandfathered Loan
- Original loan: $900,000 (2015) - under old $1M limit
- Refinanced: $850,000 (2024) - reduced principal
- Result: Keep $1M limit ✓ (refi didn't increase debt)
- Interest deductible: All of it (under $1M)
Home Equity Loans & HELOCs
Critical Rule Change (2018+):
Home equity interest is only deductible if you use the money to "buy, build, or substantially improve" your home.
✅ Deductible Uses
- ✓ Kitchen remodel
- ✓ Bathroom addition
- ✓ New roof
- ✓ HVAC system replacement
- ✓ Room addition
- ✓ Deck or patio construction
- ✓ Solar panel installation
❌ Not Deductible
- ✗ Pay off credit cards
- ✗ Car purchase
- ✗ Vacation
- ✗ College tuition
- ✗ Wedding expenses
- ✗ Business investment
- ✗ Stock purchases
Important: Home equity loan counts toward $750k limit. If you have $700k mortgage + $100k HELOC, only $50k of HELOC interest is deductible.
📋 Form 1098: Mortgage Interest Statement
Your lender sends Form 1098 by January 31 showing:
- Box 1: Mortgage interest paid (report on Schedule A, Line 8a)
- Box 2: Outstanding mortgage principal (for debt limit calculation)
- Box 3: Mortgage origination date
- Box 4: Refund of overpaid interest
- Box 5: Mortgage insurance premiums (may be deductible if under income limit)
- Box 6: Points paid on purchase (fully deductible in year of purchase)
Points: Mortgage Origination Fees
Purchase: Deduct Immediately
If you pay points when buying your home:
- ✓ Fully deductible in year of purchase
- ✓ Example: 1 point on $500k loan = $5,000 deduction
- ✓ Shows in Box 6 of Form 1098
Refinance: Amortize Over Loan Life
If you pay points when refinancing:
- • Must spread deduction over life of loan
- • Example: $3,000 points on 30-year refi = $100/year deduction
- • Exception: Pay off early, deduct remaining points in final year
Mortgage Insurance Premiums (PMI)
PMI deduction expired after 2021. Congress may extend it, but as of 2025, PMI is NOT deductible.
Check current year tax law or IRS.gov for updates. Previously, PMI was deductible for HOH filers with AGI under ~$109,000 (phase-out).
Second Home Rules
You can deduct mortgage interest on one second home (vacation home, rental property used personally).
Combined Limit Applies:
Primary + second home debt must total under $750,000 for full deduction.
Example: $600k primary + $300k vacation home = $900k total → Only $750k of debt qualifies
Rental Property Exception:
If you rent out second home more than 14 days AND use personally ≤ 14 days (or 10% of rental days), it becomes rental property with different rules (Schedule E instead of mortgage deduction).
⚠️ Common Mistakes
Deducting Home Equity Interest for Non-Home Uses
Only deductible if funds used for home improvements. Keep receipts!
Forgetting to Prorate Above Debt Limit
If mortgage > $750k, must calculate: (Limit / Loan) × Interest Paid
Deducting Principal Payments
Only INTEREST is deductible, not principal reduction.
Missing Refinance Points Deduction
Don't forget annual amortization of refinance points (small but adds up).
💡 Tax Planning Strategies
1. Bunch Deductions in Alternating Years
If you're close to $22,500 threshold, prepay January mortgage payment in December to push itemized deductions higher in one year.
2. Accelerate Home Improvements
If using HELOC for remodel, bunch improvements into one year to maximize itemized deductions.
3. Time Refinancing Strategically
Refinance points spread over loan life hurt deductions. If rates drop significantly, benefits may outweigh smaller yearly point deduction.
4. Consider 15-Year vs 30-Year Mortgage
15-year = less total interest = lower deduction BUT save on interest cost. Most people overpay on 30-year for tax deduction that isn't worth it.