Most business owners know the big-ticket deductions — rent, payroll, and office supplies — but some of the best deductions are hiding in plain sight.

Freelancing is exciting — you set your own schedule, choose your clients, and work from anywhere. But with that freedom comes a new set of responsibilities, especially when it comes to taxes. Many freelancers wait until April to think about tax season, but staying organized all year long will save you stress and money.

When a taxpayer is considered a resident under the domestic law of two countries for the same tax year, both jurisdictions may claim the...