What it means
Mortgages are ranked by priority, generally in the order they are registered against the property. The first mortgage sits at the top of that queue, which is the single fact that determines both its interest rate and its terms.
Priority matters only when something goes wrong. In a normal sale the order is irrelevant because all lenders are repaid from the proceeds, but in a forced sale the first mortgage lender takes everything it is owed before anyone below it receives a cent.
That protection is why first mortgage rates are lower. A lender that is confident of recovering its money from a sale can accept a thinner margin, while a second charge lender prices in the real possibility of receiving only part of what it is owed.
For borrowers, the practical constraint is loan-to-value, which is the loan amount divided by the property value. Most first mortgage lenders cap this somewhere between 60% and 80% for commercial property and higher for residential, and the cap effectively sets how much equity the borrower must contribute.
A nuance worth knowing is that priority is not always purely chronological. Refinancing a first mortgage while a second charge is in place usually requires the second lender to sign a deed of postponement, and in some jurisdictions certain claims such as unpaid property taxes rank ahead of every mortgage.
In practice
Real-world examples.
Example
A couple buying a $500,000 home with a $400,000 loan give the bank a first mortgage over the property at an 80% loan-to-value. Two years later they take a $40,000 home improvement loan secured as a second charge at a noticeably higher rate.
Example
A brewery buys a production site for $2.2 million with a $1.4 million first mortgage from a commercial bank. When it later borrows against the same site for tank expansion, the second lender charges four percentage points more purely because of its ranking.
Example
A property investor refinances a first mortgage to a cheaper lender and discovers the existing second charge holder must formally agree to keep its lower ranking. The refinance is delayed six weeks while the deed of postponement is negotiated.
Formula
Calculation
Two calculations matter. First the loan-to-value ratio:
Loan-to-Value = First Mortgage Amount / Property Value
Take a commercial unit valued at $600,000 with a first mortgage of $420,000.
Loan-to-Value = $420,000 / $600,000 = 70%
Second, the monthly repayment on a repayment mortgage:
Monthly Payment = P x i / (1 - (1 + i) ^ -n)
where P is $420,000, i is the monthly rate of 6% / 12 = 0.005, and n is 360 months.
Monthly Payment = $2,518.11
In the first month, interest is $420,000 x 0.005 = $2,100.00, so only $418.11 reduces the balance.
Now test the priority. If the borrower defaults and the property sells for just $450,000 net of costs, the first mortgage lender takes its $420,000 in full. A second charge lender owed $60,000 receives the remaining $30,000, recovering 50% of its loan, which is exactly the risk its higher rate was pricing.Case study
Seen in the real world.
Thornbury Dental Group is an invented business used here for illustrative purposes only. It bought a clinic building for $1,000,000 using a $700,000 first mortgage and $300,000 of its own cash, giving a 70% loan-to-value at a rate of 6%.
Three years later the practice needed $180,000 for equipment and approached a second lender, who offered a second charge over the same building at 11.5%. The partners were surprised at the gap until the lender showed them the arithmetic: on a distressed sale at $820,000, the first mortgage balance of roughly $672,000 would leave only $148,000 against a $180,000 second charge.
In this illustrative case the partners chose asset finance secured on the equipment itself instead, at 8%, because the equipment lender ranked first against that asset. Ranking, not the borrower's quality, drove the price.
Watch out
Common mistakes.
- Assuming the first mortgage is simply the earliest loan taken out, when priority depends on registration and on any postponement agreements signed later.
- Believing a second mortgage is unavailable while a first exists, when second charges are common and simply cost more.
- Comparing a first and second mortgage rate as though the difference were a lender's margin preference, when it reflects a genuine difference in recovery risk.
Questions
People also ask.
What happens to a first mortgage when a property is sold normally?
It is repaid in full from the sale proceeds at completion, and the charge is removed from the property register.
Can a first mortgage be refinanced without the second lender's consent?
Usually not, because the new lender needs first ranking and the existing second charge holder must agree to remain behind it.
Does anything rank ahead of a first mortgage?
In many jurisdictions yes, including unpaid property taxes and certain statutory charges, which is why lenders check for them before completion.
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