Bug report

[vbolkhov]

I found a calculation bug in TurboTax Desktop (Federal, [tax year]) regarding the MFJ optional deduction (or OBBA / QBI-related worksheet).

Issue:

• TurboTax applies the 6% phase-out to the single base amount ($6,000), then multiplies the reduced result by 2 for married filing jointly.

• The IRS/statute requires that the joint base ($12,000) be established first, then the 6% phase-out applied once based on joint income above $150,000.

• The current sequence under-calculates the deduction. For example:

  • Correct: $12,000 − [(Joint Income − 150,000) × 0.06]

  • TurboTax: (6,000 − [(Joint Income − 150,000) × 0.06]) × 2

• The base is hardcoded internally; it cannot be overridden in Forms.

Impact: The final deduction is lower than it should be. This affects the federal return for MFJ filers above the phase-out threshold.

Request: Please correct the order of operations so that the joint base is established first, then the phase-out is applied once

[VolvoGirl]

Sorry. It is phased out for EACH spouse. Fill out Sch 1-A yourself and see. It's pretty easy. Then why would they even have 2 lines 36a and 36b for spouse?

IRS Schedule 1-A
https://www.irs.gov/pub/irs-pdf/f1040s1a.pdf

IRS EXPLANATION
See IRS instructions for 1040 page 110
https://www.irs.gov/pub/irs-pdf/i1040gi.pdf
If you are married and filing jointly, both you and your spouse were born before January 2, 1961, and you both have a valid SSN, the maximum amount of the enhanced deduction for seniors is $12,000. The $6,000 per person amount is reduced if your MAGI is more than the amount shown next for your filing status.

It says PER PERSON. Also then why would they even have 2 lines 36a and 36b for spouse on Schedule 1-A?