Grantor Retained Annuity Trusts (GRAT) - Calculator

Last updated: November 5, 2025

Model the impact of funding a GRAT using Luminary’s GRAT designer. Our GRAT designer allows you to analyze the impact of various GRAT funding amounts, terms, and annuity payment options.

Our proposals break down the impact of funding a GRAT in terms of wealth transferred and estate tax savings, making it easy for you to explain the strategy to your clients.

If you have already funded a GRAT and are looking for details on how to enter an existing GRAT in Luminary, skip to this page: Existing GRATs

To start modeling a GRAT, navigate to Calculator > GRAT

  1. GRAT details

    1. Enter the desired display name for the GRAT.

    2. Select the desired Grantor.

    3. Select the desired GRAT remainder beneficiary(s) and % allocation.

  2. GRAT Assets

    1. Specify the desired asset category, name, and value of initial funding for the GRAT.

    2. Enter the assumed rate of return for the GRAT (note, this is for illustration purposes for the projected values on the right side of the page and is not applied in the waterfall.)

  3. GRAT Term

    1. Specify the GRAT term length and 7520 rate.

      1. The current 7520 rate will be pre-populated and a link to the IRS table is provided.

  4. GRAT Annuity

    1. Specify the GRAT remainder and Annuity payment type (fixed or increasing)

      1. Select “zeroed-out” if you would like to set grantor retained interest equal to the initial funding amount, or select “taxable gift” if you would like to specify a taxable gift amount.

  5. Click Finish

Once you've designed your GRAT. You can create a GRAT proposal to illustrate outcomes based on different rates of return. Select Create New on the left to start your proposal.

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