if this year, ur income is much less:

1. u do not need to pay those 4 estimated payments by the amount and schedule the IRS or ur accountant calculated for u. u can use annulized estimated method which calculates ur est tax based on ur actual quarter income.

2. also, if u think the balance due(Line75, Form 1040. the tax u owe after deducting teh total tax payment including withheld, credit, etc) is less than $1000, u r not subject to any penalty. that means u do not need to pay those 4 estimated tax payments at all.