You need your 2018 AGI from your original tax return. If H & R Block did your 2018 return, then than you should be able to get it from them.
According to the IRS, "Adjusted Gross Income (AGI) is defined as gross income minus adjustments to income." On 2018 returns, filers can get a quick estimate of their AGI by looking at line 37 on their Form 1040.
