Data Source and Methodology
Primary source: IRS, “Instructions for Form 709 (United States Gift (and Generation‑Skipping Transfer) Tax Return)”, 2024 Revision. Direct link: irs.gov/instructions/i709. Annual exclusion and unified credit amounts for 2018–2024 are based on IRS releases (e.g., Rev. Proc. 2023‑34).
All calculations strictly follow the formulas and data provided by this source.
The Formula Explained
1. Annual exclusions:
$$E_{\text{total}} = r \times E_{y} \times s,\quad s = \begin{cases}2 & \text{if gift-splitting}\\ 1 & \text{otherwise}\end{cases}$$
2. Taxable gifts for the year:
$$T = \max\left(0,\; G - E_{\text{total}} - C - M\right)$$
3. Effective lifetime exemption:
$$L_{\text{eff}} = s \times L_{y}$$
4. Exemption used by this gift:
$$U = \min\left(T,\; \max(0, L_{\text{eff}} - P)\right)$$
5. Estimated tax due now (τ is the progressive gift tax function from IRS rate schedule):
$$\text{TaxDue} = \tau\!\left(\max\!\left(0, P+T - L_{\text{eff}}\right)\right) - \tau\!\left(\max\!\left(0, P - L_{\text{eff}}\right)\right)$$
Glossary of Variables
How It Works: A Step-by-Step Example
Scenario (2024): You and your spouse give a total of $100,000 to two adult children, elect gift‑splitting, and have no prior taxable gifts. No charitable or marital deductions apply.
- Annual exclusion per donor per donee is $18,000. With gift‑splitting, per donee exclusion doubles to $36,000. With 2 recipients: $36,000 × 2 = $72,000.
- Taxable gifts for the year: $100,000 − $72,000 = $28,000.
- Combined lifetime exemption: 2 × $13,610,000 = $27,220,000. Prior taxable gifts P = $0.
- Exemption used now: min($28,000, $27,220,000) = $28,000.
- Amount over exemption: $0 → Estimated gift tax due: $0.
- Form 709 filing is still required because you elected gift‑splitting.