There are various strategies that can be used by someone with a job to avoid paying estimated taxes with respect to income not subject to withholding. Some strategies include:
However, be sure that the strategies you use address not only the income tax on your contract work but also any self-employment tax that may be owed.
A tax technique of applying a loss or credit from a current year to a later year. For example, a business net operating loss may be carried forward 20 years instead of being carried back.