"and the employee contributes 1/2 from their own salary and 1/2 from the company assets. I didn't think I needed to get into the weeds on the specifics of the plan in this question, because "pension" covers multiple types of plans that all have similar rules, so I used the generic term."

No, details matter. Here's an example, right here in your topic:

https://www.irs.gov/retirement-plans/plan-participant-employee/retirement-topics-simple-ira-contribu...

"Salary reduction contributions 

The amount an employee contributes from their salary to a SIMPLE IRA cannot exceed $16,000 in 2024 ($15,500 in 2023; $14,000 in 2022; $13,500 in 2020 and 2021; $13,000 in 2019 and $12,500 in 2015 – 2018).

If an employee participates in any other employer plan during the year and has elective salary reductions under those plans, the total amount of the salary reduction contributions that an employee can make to all the plans he or she participates in is limited to $23,000 in 2024 ($22,500 in 2023; $20,500 in 2022; $19,500 in 2020 and 2021 and $19,000 in 2019). See more than one plan.

• Catch-up contributions. If permitted by the SIMPLE IRA plan, participants who are age 50 or over at the end of the calendar year can also make catch-up contributions. The catch-up contribution limit for SIMPLE IRA plans is $3,500 in 2023 and 2024 ($3,000 in 2015 - 2022)."

That means your taxpayer contributes up to $19,000 for 2023 if over 50, all of this will be from Wages.

"Employer matching contributions

The employer is generally required to match each employee's salary reduction contributions on a dollar-for-dollar basis up to 3% of the employee's compensation. This requirement does not apply if the employer makes nonelective contributions instead.

• Lower percentage. An employer may choose to make a matching contribution less than 3%, but it must be at least 1% and for no more than 2 out of 5 years. See Notice 98-4 PDF for more information. The employer must notify the employees of the lower match within a reasonable period before the 60-day election period for the calendar year."

That means the Employer doesn't contribute more than 3%, or $2,970 on $99k salary.

I can't tell you the number of fights I have had with brokers setting up the accounts for SIMPLE IRA participants. Someone isn't administering this plan properly. They confused SEP-IRA and SIMPLE IRA, perhaps.

Yes, there are other plans that provide for what you described. These shareholder-employees are treated as self-employed for some things, as employee for others. But SIMPLE IRA is its own provision. It can be tricky:

https://www.irs.gov/retirement-plans/retirement-plans-for-self-employed-people