One of my clients is getting estimated worksheets for 2020, when they are receiving a small refund this year. 

The 2020 Estimated Tax Worksheet shows, if same income is generated, and same taxes are withheld next year (on clients fixed income)  Lacerte computes they will owe significantly more, than allowably owing without penalty.

Why is this so much different than this year? Is this accurate?

If they are on a fixed income and budget is tight, I do not want them paying out large estimate prepayment for 2020, if this is not accurate.  But do not want to do them a dis-service by suppressing estimates. Should I trust Lacerte's worksheet?