Notes

This book gives general information about an everyday habit. It isn't financial advice, and it's no substitute for a debt adviser who knows your situation. The organisations I mention are free UK services as I found them in September 2026. No product, lender or rate is recommended, and the sums in the chapters are round and made up to illustrate.

I've kept sources out of the chapters where I could so they read easily. Here they are by chapter, with the limits I'm aware of. Unless I say otherwise, I read the published summary of each paper and not the full text. I checked each paper for a retraction or correction notice in September 2026 and found none. Where a chapter isn't listed, it rests on my own reasoning. That includes chapters 1, 2, 7, 9, 13, 15, 18, 19, 21, 24 and 25. The app, the coat, the boiler, the second card and the colleague who clears monthly are invented.

Before you start. StepChange, Citizens Advice and National Debtline are named on the NHS page on financial worries, as verified for earlier books in this series. The two-week guide for low mood is from the NHS pages on depression.

Chapter 3. Shefrin and Thaler, "The behavioral life-cycle hypothesis", Economic Inquiry 26, 1988, pages 609 to 643, as verified for the earlier book Pay yourself on payday. The claim about how limits are set is my reasoning and not a finding.

Chapter 4. Prelec and Loewenstein, "The red and the black: mental accounting of savings and debt", Marketing Science 17, 1998, pages 4 to 28. Raghubir and Srivastava, "Monopoly money: the effect of payment coupling and form on spending behavior", Journal of Experimental Psychology: Applied 14, 2008, pages 213 to 225. Both as verified for the earlier book You didn't want it yesterday.

Chapter 5. StepChange, "Credit card debt", for the persistent debt rule as they describe it. Stewart, "The cost of anchoring on credit-card minimum repayments", Psychological Science 20, 2009, pages 39 to 41. The summary gives no effect size and none is given here. Navarro-Martinez, Salisbury, Lemon, Stewart, Matthews and Harris, "Minimum required payment and supplemental information disclosure effects on consumer debt repayment decisions", Journal of Marketing Research 48, 2011, pages S60 to S77. American experiments and British field data. The inference about why the minimum is set where it is, is mine.

Chapter 6. StepChange as above, for the £1,000 at 20 per cent illustration. Soll, Keeney and Larrick, "Consumer misunderstanding of credit card use, payments, and debt: causes and solutions", Journal of Public Policy and Marketing 32, 2012. American statements, which the chapter says. The coat's real price is my arithmetic.

Chapter 8. Sussman and Alter, "The exception is the rule: underestimating and overspending on exceptional expenses", Journal of Consumer Research 39, 2012, pages 800 to 814, as verified for the earlier book Pay yourself on payday.

Chapter 10. StepChange as above, for around 18 million people. The earlier book on spending to keep up is Ask the price of the evening.

Chapter 11. Gathergood, Mahoney, Stewart and Weber, "How do individuals repay their debt? The balance-matching heuristic", American Economic Review 109, 2019. Linked data on multiple cards.

Chapter 12. StepChange as above, for balance transfers as one option. The observation about the old card staying in the wallet is mine.

Chapter 14. Soll and colleagues as above. The earlier book on the unopened letter is in this series.

Chapter 16. StepChange as above, for the persistent debt rule.

Chapter 17. StepChange as above, for sleepless nights, defaults and the credit file. The interest figures are illustrative arithmetic at 20 per cent.

Chapter 20. Gathergood and colleagues as above. The earlier book on the payday transfer is Pay yourself on payday. StepChange as above.

Chapter 21. Prelec and Loewenstein as above. The earlier books on spending to keep up and on saving as above.

Chapter 22. Gollwitzer and Sheeran, "Implementation intentions and goal achievement: a meta-analysis of effects and processes", Advances in Experimental Social Psychology 38, 2006, pages 69 to 119. The rule hasn't been tested as a package, and what I say to expect is my expectation and not a finding.

Chapter 23. StepChange as above, and the NHS page on financial worries. The earlier book on raising difficult things is Say it this week. The earlier book on buying when low is You didn't want it yesterday.