Self-Employment Taxes

The Royalty checks for writing a book is considered income subject to self-employment tax if the recipient can be considered to be regularly engaged in that business or profession and will report this activity on a Schedule C.
The Royalty checks for writing a book is not considered income subject to self-employment tax if the recipient writes only one book as a sideline and will report this activity on a Schedule E

As a self-employed individual, you should keep your payroll records for seven years, business income and deduction records for six years after the tax return is filed, and copies of your business tax returns should always be kept.