My first year freelancing I earned 31,000 pounds, spent most of it, and then opened a brown envelope in January asking for 6,400 pounds by the end of the month. I had heard of payments on account. I had not understood that they applied to me.

I am Jess Catto. I have worked as a freelance designer and illustrator for over a decade, and Catto Creations has quietly turned from a portfolio site into the place where I write down what I have learned about the money side of that life. Self-assessment and the deadlines that bite twice a year. IR35 and what it means when a client suddenly wants you on payroll. Day rates versus project fees. Chasing invoices without losing the client. Pensions when nobody is paying in for you.

Everything is worked in pounds from my own books, anonymised where clients are involved. I have got plenty wrong: under-priced a retainer for two years, ignored a pension until my late thirties, paid an accountant for work I could have done in an afternoon. Those mistakes are in here too.

Each article ends with what I would do, not with a suggestion to see an adviser. Catto Creations is an independent UK publication and none of it is personal financial advice; it is one working freelancer showing her numbers.