I do think the Federal bracket tax rates may be going up next year so I will use those.

The 2018 Tax Cuts and Jobs Act tax bracket changes are set to expire AFTER 2025, so starting with the 2026 tax year.

My estimates for what the

2017 tax brackets would be for Married Filing Jointly if still in effect in 2024 are below. These will go up with inflation by 2026, but as long as you're using inflation adjusted return assumptions in your spreadsheet you should be using current tax brackets anyway. The way I've calculated this is by scaling the brackets with the Personal Exemption ($4050 in 2017) which was the same as the Qualified Disability Trust exemption that's still published ($5000 in 2024).

$0 - $23,000 10.00%

$23,000 - $93,700 15.00%

$93,700 - $189,000 25.00%

$189,000 - $288,050 28.00%

$288,050 - $514,400 33.00%

$514,400 - $581,100 35.00%

over $581,100 39.60%

Standard deduction $15,650

Personal exemption $5,000

Personal exemption phaseout $387,400

The personal exemption phaseout subtracted 2% of the personal exemption for every $2500 you were over the phaseout amount. The $2500 didn't increase with inflation, so I don't know if it would be any higher in 2026.