Fixed, Variable, and Split Loans: What Not to Do

Most FIFO mining engineers pick a loan structure based on the rate they see advertised, not on how that structure handles the way they actually repay.

You earn more on-roster than off, you might throw extra cash at the loan between swings, and you need to know whether your loan will penalise you for that or let you get ahead. Fixed, variable, and split loans each respond differently to that repayment behaviour, and the wrong pick can cost you thousands or lock you into a structure that fights your financial habits.

Fixed Rate Loans Lock Your Rate and Your Flexibility

A fixed rate home loan holds your interest rate steady for a set period, usually between one and five years. You know exactly what you'll pay each month, and rate rises during that period don't touch you.

The limitation shows up when you want to make extra repayments. Most fixed rate products cap additional repayments at $10,000 to $30,000 per year depending on the lender. If you're earning $180,000 and want to throw $40,000 at your loan in a good year, the excess gets hit with a penalty, or you can't make the payment at all. Break costs also apply if you refinance, sell, or switch to a variable rate before the fixed term ends. Those costs are calculated on the difference between your fixed rate and the lender's current wholesale funding rate, and they're not small when rates have dropped since you locked in.

Consider a mining engineer who fixed $600,000 at 5.8% for three years in late 2024. Eighteen months later, variable rates sit closer to 5.2%. If he wants to refinance to access equity for an investment property, the lender calculates break costs on the remaining term and loan balance. That bill could easily run to $15,000 or more, which wipes out most of the benefit he was chasing by refinancing.

Variable Rate Loans Respond to Every Rate Move and Every Extra Dollar

A variable rate home loan moves with the lender's standard rate, which tracks the Reserve Bank cash rate and funding costs. When rates drop, your repayments drop. When they rise, so do your repayments.

The upside is flexibility. You can make unlimited extra repayments without penalty, redraw those funds if the loan allows it, and refinance your home loan or pay out the loan in full at any time without break costs. If you're the kind of borrower who pays extra during high-income months and redraws during time off, a variable rate loan gives you room to move.

The risk is rate exposure. A variable rate that starts at 5.9% could move to 6.5% or higher depending on economic conditions. On a $600,000 loan, a 0.6% increase adds roughly $230 to your monthly repayment. If you're managing that on a tight budget during off-roster periods, the swing can pinch.

Split Loans Give You Both Structures in One Package

A split loan divides your loan amount between a fixed portion and a variable portion. You might fix 50% of your borrowing at 5.7% for three years and leave the other 50% on a variable rate at 5.9%.

This structure lets you lock in certainty on part of your repayment while keeping flexibility on the rest. If rates rise, your fixed portion stays put. If rates fall, your variable portion drops with them. You can make extra repayments on the variable portion without hitting the caps that apply to the fixed side, and you avoid paying break costs on the entire balance if you need to refinance or restructure before the fixed term ends.

The downside is complexity. You're managing two loan accounts, sometimes with different repayment schedules, and if you want to adjust the split ratio later, you'll need to refinance one or both portions. Some lenders also charge two sets of fees, one for each side of the split, though that's less common now.

In a scenario where a FIFO mining engineer borrows $650,000 and splits it 60/40 between fixed and variable, the fixed portion of $390,000 holds steady at 5.6%, while the variable portion of $260,000 starts at 5.8%. He makes extra repayments of $20,000 per year on the variable portion during high-income periods. After three years, the fixed portion reverts to variable, and he refinances the entire balance to access equity without paying break costs on funds he's already paid down.

Offset Accounts Work Differently Depending on Your Loan Structure

An offset account is a transaction account linked to your home loan. The balance in the offset reduces the amount of interest you're charged without affecting your actual loan balance. If you have a $600,000 loan and $40,000 sitting in a linked offset account, you only pay interest on $560,000.

Offset accounts are typically available on variable rate loans and on the variable portion of a split loan. They're rarely offered on fully fixed loans, and when they are, the offset benefit is often partial rather than full. For FIFO workers who bank large pay packets during roster periods, an offset account lets you reduce interest costs without committing those funds as extra repayments. If you need the cash later, it's still there.

The benefit depends on your loan balance and how much you keep in the offset. At current variable rates around 5.9%, a $40,000 offset balance saves roughly $2,360 in interest per year on a $600,000 loan. That's more effective than leaving the same cash in a savings account earning 2.5% after tax.

How FIFO Income Patterns Change the Calculation

FIFO income is lumpier than a standard fortnightly salary, and that changes how each loan structure performs. If you're earning $14,000 a fortnight on-roster and $3,000 a fortnight on leave, you'll have surplus cash during roster swings and tighter cash flow during time off.

A variable rate loan with an offset account lets you park surplus income during roster periods, reduce your interest bill, and pull funds back out when you're off-roster. A fixed rate loan without offset or with limited extra repayment capacity forces you to either lock that cash into the loan or leave it sitting in a low-interest savings account. A split loan gives you both options, but only on the variable side.

Lenders assess your income differently depending on your employment structure. Most will average your last two years of income if you've been in the same role, or they'll apply a discount to your on-roster rate to account for downtime. That calculation affects how much you can borrow, but it also matters when you're choosing your loan structure. If the lender is already discounting your income for serviceability, taking on a fixed rate loan that limits your ability to pay down the balance quickly might not align with how you plan to manage the debt.

When Fixing Part of Your Loan Makes Sense

Fixing part of your loan makes sense when you want to lock in a portion of your repayment and protect yourself from rate rises, but you still want room to make extra repayments and access equity if needed. It's a middle option that works if you're uncertain about rate direction but don't want to be fully exposed.

It doesn't make sense if you're planning to sell or refinance within the fixed term, or if you're confident you'll want to make large extra repayments across the full loan balance. In that case, a variable rate loan with offset and unlimited extra repayment capacity is the better fit.

For FIFO mining engineers, the split structure often aligns with the way income flows. You fix the portion that covers your baseline repayment during off-roster periods, and you keep the rest variable so you can attack it during high-income months without restriction.

What Not to Do When Choosing Your Loan Structure

Don't pick a fixed rate loan just because the advertised rate is 0.2% lower than variable. That difference disappears the moment you want to make an extra repayment beyond the cap or refinance before the term ends.

Don't assume a split loan is always the middle ground. If you split 80% fixed and 20% variable, you've still got most of your loan locked in with limited flexibility. The ratio matters as much as the structure.

Don't ignore how your lender treats your FIFO income when setting your borrowing limit. If they're already shaving 20% off your on-roster income for serviceability, you need a loan structure that lets you pay down debt fast when you've got the cash, not one that caps your extra repayments at $20,000 a year.

And don't forget that interest rate environments change. A fixed rate that looks solid now might look expensive in two years, and break costs are calculated to recover the lender's loss, not to give you an exit ramp.

Call one of our team or book an appointment at a time that works for you. We'll walk through your roster, your income pattern, and your plans for the property, then match you to a loan structure that fits how you actually operate, not just the rate on the comparison table.

Frequently Asked Questions