Pro Tier Module
Tax Deadline & Late-Penalty Calculator (Federal)
Federal filing deadlines plus exact IRC late penalties, with the dated interest rate you confirm.
This tool runs inside GDBS Pro. What it computes and the authorities it applies are below.
The problem
Late-return penalties stack the failure-to-file and failure-to-pay charges, reduce one when both run, apply a >60-day minimum, and accrue interest at a quarterly federal rate. Getting the deadline roll or the penalty interaction wrong misstates a client's exposure.
The local-first solution
This plugin computes the unextended and extended federal due dates with the weekend/holiday roll, then the IRC 6651 penalties and their interaction, surfacing the dated 6621 interest rate you confirm. It is exact date and penalty arithmetic, runs in your browser, and cites every rule - nothing is uploaded.
What it does
Filing and extension due dates for Forms 1040, 1120, 1120-S, and 1065
Weekend and federal-holiday roll under IRC 7503
Failure-to-file at 5%/month, capped at 25% (6651(a)(1))
Failure-to-pay at 0.5%/month, capped at 25% (6651(a)(2))
Penalty interaction reducing FTF to 4.5%/month while FTP runs
>60-day minimum and IRC 6601 interest at the dated rate you confirm
Honest scope
Federal only and not tax advice; state deadlines and rates are not computed. The penalty rates and caps are fixed in the statute and exact, but the IRC 6621 interest rate and the >60-day dollar floor are dated inputs you confirm. Interest is a simple-proration estimate - the IRS compounds daily under IRC 6622. Fraudulent-failure-to-file, reasonable-cause or first-time abatement, and the estimated-tax and accuracy penalties are not modeled.
Authorities cited
- IRC 6651(a)(1) - Failure to file: 5% of the unpaid tax for each month or fraction of a month, not to exceed 25%.
- IRC 6651(a)(2) - Failure to pay: 0.5% of the unpaid tax for each month or fraction, not to exceed 25%.
- IRC 6651(b) - The penalties are computed on the net amount of tax required to be shown (reduced by timely payments/credits).
- IRC 6651(c)(1) - When both penalties apply for the same month, the failure-to-file rate is reduced by the failure-to-pay rate (5% - 0.5% = 4.5%).
- IRC 6651(a) (flush sentence) - If a return is more than 60 days late, the minimum failure-to-file penalty is the lesser of a stated dollar amount (inflation-adjusted) or 100% of the tax required to be shown.
- IRC 6601 - Interest on underpayment, accruing from the last date prescribed for payment.
- IRC 6621 - The underpayment interest RATE, set QUARTERLY by the IRS (federal short-term rate + 3%). Confirm the current quarter rate.
- IRC 6622 - Interest is compounded daily (this plugin estimates with simple daily proration; confirm a binding figure).
- IRC 6072 / 6081 - Statutory due dates and automatic filing extensions for 1040 / 1120 / 1120-S / 1065.
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Calculate deadlines and penalties
Run the deadline and penalty math in your browser and route the result into a Sandbox workspace or attach it to a Worklog case. Nothing is uploaded to anyone's cloud.