I think that is when it phases out, not when it phases in.
Table 3. 2019 Alternative Minimum Tax Exemptions
Filing Status Exemption Amount
Unmarried Individuals $71,700
Married Filing Jointly $111,700
In 2019, the 28 percent AMT rate applies to excess AMTI of $194,800 for all taxpayers ($97,400 for married couples filing separate returns).
AMT exemptions phase out at 25 cents per dollar earned once taxpayer AMTI hits a certain threshold. In 2019, the exemption will start phasing out at $510,300 in AMTI for single filers and $1,020,600 for married taxpayers filing jointly (Table 4).