Jasmine Birtles
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How to Invest If You Have Debt: Pay It Off First, or Invest?
Moneymagpie Team
4th Nov 2026
You have got a bit of spare cash each month, a head full of “I should really start investing” and a credit card balance that refuses to budge.
So which comes first? It is one of the most common money dilemmas out there, and the answer is not the same for everyone. Don’t worry, we’ll walk through it, with a simple order of play you can follow.
The short answer
For most people, the sensible order is to deal with expensive debt first, build a small emergency fund, and then invest. MoneyHelper, the free government-backed money guidance service, puts it this way in its guide to paying off debt, saving or investing first: the general rule is to deal with any expensive debts and build up an emergency fund, and only then invest money you won’t need for several years.
Why? Because it comes down to a simple comparison: what does the debt cost you, versus what could your money earn?
Why expensive debt usually wins
Interest on debt is a guaranteed cost. Investment returns are not guaranteed, and the value of investments can go down as well as up. MoneyHelper notes that you’ll rarely earn more on your savings than you’ll pay on your borrowings.
Here is a hypothetical illustration, not a forecast. Say you have £2,000 on a credit card charging 22% APR (the annual interest rate). Leave it untouched for a year and it could cost you roughly £440 in interest.
For investing to beat that, your £2,000 would need to grow by more than 22% a year, every year, and nobody can promise that. Paying off the card is effectively a risk-free return equal to the interest rate you stop paying.
Which debts are “expensive”?
MoneyHelper lists the usual suspects as most credit cards, store cards, unauthorised overdrafts, catalogue shopping, payday or short-term loans and home credit. These are typically the costliest because they are unsecured. Check the APR on your statements and rank your debts from highest to lowest rate. Pay the minimum on everything, and throw any extra at the highest-rate debt first.
Cheaper debts are a different story
A low-rate loan or mortgage is a different calculation.
If a debt is cheap, it may make sense to pay it off on schedule while also saving or investing. MoneyHelper still advises clearing higher-interest debts before making extra mortgage repayments, and checking for early repayment charges, especially on a fixed-rate deal.
Student loans are not like other debts
UK student loans work differently. According to GOV.UK, repayments are a percentage of your income above a threshold (9% for Plans 1, 2, 4 and 5, and 6% for a Postgraduate Loan), taken automatically from your pay.
There is no fixed monthly bill, your balance doesn’t change what you repay, and you pay nothing if you earn below the threshold, although interest still builds up. Because of this, many people treat a student loan quite differently from a credit card. Before making voluntary overpayments, check the terms of your plan.
Don’t skip the emergency fund
It is tempting to throw every penny at debt, but with no cushion, a broken boiler or a car repair ends up back on the credit card. MoneyHelper suggests aiming for three to six months of living costs, but says any amount helps, and that consistency is key, even if it is small amounts each month.
If you have expensive debt, it generally says to clear that first, so a good middle route is a small starter buffer, then attack the debt, then top the fund up.
What about a workplace pension?
Pensions are a form of long-term investing, and MoneyHelper calls them a tax-efficient way of investing for the long term. If your employer adds money when you contribute, missing out means turning down part of your pay. Many people keep their workplace pension going while paying off debt, but it is worth checking what works for your budget.
A simple step-by-step plan
- Sort priority debts first. Things with serious consequences, such as council tax arrears or court fines, come before everything else.
- Pay the minimums on all your debts so you avoid charges and damage to your credit rating.
- Build a starter emergency fund. Even a month’s essential costs is a good start.
- Attack your highest-interest debt. Use any extra cash on the debt with the highest APR, then roll that payment onto the next one.
- Top up your emergency fund towards three to six months of expenses.
- Start investing. Begin with money you won’t need for at least five years. Our 5-minute investing starter checklist is a good place to begin, and you can see how much money you need to start investing. Then read our guide to stock investing for complete beginners.
Can you do both at once?
Sometimes. If your only debts are cheap, such as a low-rate loan, splitting spare cash between debt repayment and small regular investments can work, and it helps you build the habit. If you have credit card or other high-interest debts, though, clearing those first is usually the better use of your money.
If your debt feels unmanageable
If you are already missing payments or struggling, please don’t go it alone. MoneyHelper recommends free, impartial debt advice, and has a debt advice locator to find services near you. You should never have to pay for help with debt.
Disclaimer: This article is for informational and educational purposes only and is not regulated financial advice. Investing involves risk, and the value of your investments can go down as well as up, so you could get back less than you put in. The numbers used are hypothetical illustrations, not forecasts, and personal circumstances differ. Rates, thresholds and rules can change. Do your own research or speak to a regulated financial adviser or a free debt adviser before making decisions.
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