As a window prostitute, you are seen as an independent entrepreneur. Independent entrepreneurs are obliged to register with the Kamer van Koophandel (KvK). The KvK registers you with the Tax Department. As soon as this is done, you will receive a letter from the Tax Department stating when you have to file your turnover tax and income tax returns. This means that you have to state how much you have earned. Some costs related to your work (with the exception of clothing and personal care) can be deducted from the money you have earned. You must file a turnover tax return once every three months. You also submit income tax returns once a year. You can have the returns prepared via an accountant. To submit a good tax return, you need to know the amount of your turnover and how much your expenses are. You must therefore keep track of your income and expenses in a cash journal. View an example of how this looks.