IRS Safe Harbor Rule for Tax Payments

Thanks so much for your reply.  I want to make sure I understand the math behind the numbers you provided. Here is my take on how you derived them:

* The 2023 Overpayment Applied to 2024 is included in full in Q1 2024.

* The Estimated Tax Payments are included in full in the quarters they are made (Q1 and Q3 2024 in my example) 

* The Withholding Tax is assumed to have been paid evenly over 4 quarters in 2024 (even if it wasn't paid evenly?)

* The Safe Harbor threshhold amount ($16,237) is spread evenly over 4 quarters in 2024.

* The cumulative tax payments in each quarter must be greater than the cumulative threshhold amounts each quarter.

* Here is the calculation as I understand it (there may be minor rounding differences):

                                                                          Q1                  Q2                  Q3                 Q4                   Total

2023 Overpayment Applied                 $4,377                                                                                     $4,377 

2024 Withholding Tax                               1,379             1,379            1,379              1,379                 5,517

Q1 2024 Estimated Tax Payment            5,250                                                                                       5,250

Q3 2024 Estimated Tax Payment                                                          3,000                                         3,000

Total                                                           11,006              1,379            4,379              1,379              18,144

Cumulative Total                                     11,006            12,385          16,764            18,144

2024 Safe Harbor Threshold                  4,059               4,059            4,059              4,059              16,237         

Cumulative Safe Harbor Threshold       4,059              8,118          12,177            16,237

Difference in Cumulative Amounts      6,947               4,267            4,587               1,907 

Conclusion:

Since the cumulative taxes paid exceed the cumulative Safe Harbor threshhold in each quarter, the Safe Harbor requirement is satisfied.  Any additional tax owed for 2024, regardless of the amount, can be paid without penalty when the tax return is filed on April 15, 2025.

Thanks again!