google says yes a solo 401K and a SEP

I didn't go down that rabbit hole to get you limits 

Yes, but why?  The employer contribution limits don't increase by spreading it out between two plans.

Are these plans both established by the same business, this person's SE operation? Is that a solo 401(k) or regular (with employees)? Are there employees?

How old is your taxpayer? What does the software give for the amount they can contribute to each plan?

Yes, both plans are linked to her sole-proprietorship.  In 2023, she contributed $30,000 to her solo 401k and maxed out her SEP for $13,632. These are the max amounts calculated in Proseries on her $73,340 schedule C income.  She is 62 years old and had no employees.  Thank you.

Also, is there a cap on the total contributions or do I use the contribution limits for each plan?

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@pamnicholea wrote:

In 2023, she contributed $30,000 to her solo 401k and maxed out her SEP for $13,632. 

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Assuming she is age 50 or older, $30,000 was the maximum employee deferral amount.  

The $13,632 is the employer contribution.  A SEP was fine, but she could have also put it into the 401k instead.  There was no need for a separate retirement account for that.

401(k): $23,500 employee contribution max + $7,500 catch up amount for being 50-59 (which is why I asked her age) = $31,000

The self-employed "employer" share always is a bit recursive. It's around 20-25% of the gross.

"is there a cap on the total contributions or do I use the contribution limits for each plan"

Same employee, no matter how many employers = one annual limit.

Same employer, no matter how many plans = one annual limit.