Oh do all his customers give him a 1099NEC? You might have to keep track of the sales tax. How are you entering the sales you don't get a 1099NEC? Are you including the sales tax in the income? I would enter ALL the income with the Sales tax. Then expense the whole amount you pay to Washington under Taxes and Licenses on Schedule C line 23.
If you have the Online version or even in the Desktop program just enter your total business income as Cash or General. You don't need to enter the actual 1099Misc or 1099NEC. Only the total goes to schedule C line 1.
Where to enter expenses in the Online Self Employed version
https://ttlc.intuit.com/questions/3636848-where-do-i-enter-my-self-employment-business-expenses-like...
