You can deduct any ordinary and necessary expense you incurred to produce your income. The only thing that has changed for self-employed individuals is that entertainment is no longer deductible and the introduction of the QBI.

Q4. What is qualified business income (QBI)?

A4. QBI is the net amount of qualified items of income, gain, deduction and loss from any qualified trade or business. Only items included in taxable income are counted. In addition, the items must be effectively connected with a U.S. trade or business. Items such as capital gains and losses, certain dividends and interest income are exclude