Principal and Interest (P&I) is a loan repayment structure where each payment covers both the loan principal (the amount you borrowed) and the interest charged by the lender. It's the most common repayment type for home loans, car loans, and personal loans.
How P&I Repayments Work
Each repayment is split into two components:
- Principal: Pays down the actual loan balance
- Interest: Pays the lender's fee for borrowing money
Example: $500,000 home loan at 6.00% p.a. over 30 years
- Monthly repayment: $2,997
- Month 1 breakdown:
- Interest: $2,500 (500K × 6% ÷ 12)
- Principal: $497
- New balance: $499,503
Over time, as the loan balance shrinks, more of each repayment goes toward principal and less toward interest.
Repayment Breakdown Over Time
Example: $500,000 loan at 6.00% over 30 years
Year 1 (Month 1):
- Repayment: $2,997
- Interest: $2,500 (83%)
- Principal: $497 (17%)
Year 10 (Month 120):
- Repayment: $2,997
- Interest: $2,150 (72%)
- Principal: $847 (28%)
Year 20 (Month 240):
- Repayment: $2,997
- Interest: $1,380 (46%)
- Principal: $1,617 (54%)
Year 30 (Month 360 - final payment):
- Repayment: $2,997
- Interest: $15 (0.5%)
- Principal: $2,982 (99.5%)
Why P&I Is the Standard
1. You're Building Equity
Every repayment reduces your loan balance, increasing the portion of your property/asset you own outright.
Example: $500,000 loan, $650,000 property value
- Year 0: $150,000 equity (deposit)
- Year 5: $200,000 equity ($50K paid off)
- Year 10: $270,000 equity ($120K paid off)
- Year 15: $360,000 equity ($210K paid off)
2. Lower Total Interest Paid
Because you're paying down the principal from day one, you pay less interest over the life of the loan compared to interest-only.
Example: $500,000 loan at 6.00% over 30 years
- P&I: Total interest paid = $579,000
- Interest-Only for 5 years, then P&I: Total interest paid = $630,000
- Savings with P&I from day one: $51,000
3. Forced Discipline
You're required to pay down debt every month—no temptation to only pay interest.
4. Better for Owner-Occupiers
If you live in the property, P&I makes sense—you're building wealth and paying off debt.
P&I vs Interest-Only: The Numbers
Scenario: $600,000 home loan at 6.00% p.a.
Option 1: P&I for 30 Years
- Monthly repayment: $3,597
- Total paid over 30 years: $1,295,000
- Total interest: $695,000
Option 2: Interest-Only for 5 Years, Then P&I for 25 Years
-
Years 1-5 (Interest-Only):
- Monthly repayment: $3,000
- Total paid: $180,000
- Loan balance after 5 years: Still $600,000
-
Years 6-30 (P&I for 25 years):
- Monthly repayment: $3,867
- Total paid: $1,160,000
- Total interest: $560,000
-
Grand total:
- Total paid: $1,340,000
- Total interest: $740,000
- Extra cost vs P&I from day one: $45,000
When to Choose P&I
✅ Owner-Occupied Homes
If you live in the property, P&I is almost always the right choice. You're building equity and minimizing interest.
✅ Car Loans and Personal Loans
These loans are always P&I. Interest-only isn't available for consumer loans.
✅ Long-Term Wealth Building
If your goal is to own your property outright, P&I is the path.
✅ Stable Income
If your income is steady, P&I repayments (which are higher than interest-only) fit comfortably into your budget.
When Interest-Only Might Be Better
🔄 Investment Properties (Tax Strategy)
Investors often use interest-only for the first 5 years because:
- Interest is tax-deductible (principal repayments are not)
- Lower repayments free up cash for other investments
Example: $600,000 investment property
- Interest-only: $3,000/month ($36,000/year tax-deductible)
- P&I: $3,597/month ($36,000 interest + $7,164 principal)
- Only the $36,000 interest is tax-deductible in both cases
- With interest-only, the investor saves $597/month to invest elsewhere
🔄 Short-Term Ownership
If you're buying, renovating, and selling within 2-3 years, interest-only minimizes repayments during the renovation.
🔄 Cash Flow Crunch
If your income is temporarily reduced (parental leave, business startup), interest-only can lower repayments short-term.
How Extra Repayments Accelerate P&I Loans
Making extra repayments on a P&I loan saves massive amounts of interest.
Example: $500,000 loan at 6.00% over 30 years
Standard P&I:
- Monthly repayment: $2,997
- Total interest paid: $579,000
- Loan term: 30 years
P&I + $500 extra per month:
- Monthly repayment: $3,497
- Total interest paid: $403,000
- Loan term: 21 years (9 years faster!)
- Interest saved: $176,000
P&I + $1,000 extra per month:
- Monthly repayment: $3,997
- Total interest paid: $303,000
- Loan term: 16 years (14 years faster!)
- Interest saved: $276,000
Using an Offset Account with P&I
An offset account is a transaction account linked to your P&I loan. The balance in the offset account reduces the interest charged on your loan.
Example: $500,000 loan at 6.00%, $80,000 in offset account
- Interest charged on: $500,000 - $80,000 = $420,000
- Monthly interest saving: $400
- Annual interest saving: $4,800
- Over 30 years: ~$144,000 saved (if you maintain $80K in the offset)
Combined with P&I: You're paying down principal AND reducing interest with your savings.
P&I for Car Loans and Personal Loans
All consumer loans (car loans, personal loans, equipment loans) are P&I by default. You can't get interest-only on these products.
Example: $40,000 car loan at 7.00% p.a. over 5 years
- Monthly repayment: $792
- Total paid: $47,520
- Total interest: $7,520
- Loan balance reduces every month
Switching from Interest-Only to P&I
If you've been on interest-only for 5 years, your loan will automatically convert to P&I. This causes a repayment shock.
Example: $600,000 loan at 6.00%
- Years 1-5 (Interest-Only): $3,000/month
- Years 6-30 (P&I over 25 years): $3,867/month (+$867/month)
Tip: Prepare for this transition by:
- Refinancing to a 30-year P&I term (lower repayments than 25 years)
- Making extra repayments during the interest-only period to reduce the balance
- Using an offset account to reduce interest charged
Final Thoughts
P&I is the gold standard for most borrowers:
- You're paying off debt, not just servicing it
- You're building equity with every repayment
- You pay less total interest over the life of the loan
If you're an owner-occupier with stable income, P&I is the clear winner. If you're an investor, speak to a NIK Finance broker and a tax advisor about whether interest-only makes sense for your strategy.
Current rates (Feb 2026):
- P&I owner-occupied home loans: From 5.89% p.a.
- P&I car loans: From 5.99% p.a.
- P&I personal loans: From 7.99% p.a.