I completed my brother's taxes just the other day. I sent him a copy of his return and he comes back to me and asks me, "did you include...?" I had to explain to him that there have been several changes in 2018 in regards to taxes. I showed him his W-2s for both 2017 and 2018, in his case he did not make much more in 2018 than 2017, however, his taxes in 2018 were less than 2017. The biggest change that affected him is that he didn't have enough to itemize, so therefore the standard deduction was effective at $24,000 since he was filing jointly. The standard deduction for 2018 is still more than the combined standard deduction of $12,700 in the previous year and the personal exemption of $4,050 per that was allowed in 2017.
Although for my brother like everyone else did received a little extra on his paychecks in 2018 but he chose not to save it. In the end he wanted to get a bigger refund but I continue to advice him that what he really should do is adjust his withholding so he won't a refund at tax time. What he really should do is get that money throughout the year by withholding less money from his check and saving it. He might make interest on that money throughout the year instead waiting for it all at once.
I will continue to work on him. :)