Perhaps you have not really looked at the new Form 1040. It only goes to line 23, with the possible addition of six extra schedules--those schedules are only included with your tax return if the data you entered required their use. On the "old" Form 1040, line 43 had taxable income. If you are looking for that information on your 2018 return, see line 10.
https://www.irs.gov/pub/irs-pdf/f1040.pdf
https://www.irs.gov/pub/irs-pdf/f1040s1.pdf
https://www.irs.gov/pub/irs-pdf/f1040s2.pdf
https://www.irs.gov/pub/irs-pdf/f1040s3.pdf
https://www.irs.gov/pub/irs-pdf/f1040s4.pdf
Perhaps you have not really looked at the new Form 1040. It only goes to line 23, with the possible addition of six extra schedules--those schedules are only included with your tax return if the data you entered required their use. On the "old" Form 1040, line 43 had taxable income. If you are looking for that information on your 2018 return, see line 10.
https://www.irs.gov/pub/irs-pdf/f1040.pdf
https://www.irs.gov/pub/irs-pdf/f1040s1.pdf
https://www.irs.gov/pub/irs-pdf/f1040s2.pdf
https://www.irs.gov/pub/irs-pdf/f1040s3.pdf
https://www.irs.gov/pub/irs-pdf/f1040s4.pdf