LLC Partnership – Employer contribution calculation

The LLC partnership established a SIMPLE IRA for 2021. Partners are not paid via payroll and are given Guaranteed Payments. Partners are given a K1 and report their taxes as self employed people, including paying their own self employment taxes.

There are 4 partners, 2 partners are participating and have maxed out their “employee” contributions. No “employer” contributions have been made.

Who pays the “employer” contribution? If the LLC pays it, how is the contribution calculated?

If I understand correctly, the 3% employer contribution is calculated on income, less 1/2 self employment tax. But that income can not be calculated till the accounts are finalized, doing depreciation calculations etc.

And how is that then recorded in the books? After all, having the employer contributions as an additional expense affects profit/loss! Causing a circular calculation problem.

Should each partner make their own calculations and contribute them self? As per https://finance.zacks.com/deduct-selfemployed-contributions-simple-ira-3878.html

Additionally how are contributions reported on form 5498, I’m not seeing separate boxes for employee and employer contributions, are they combined or only employee contributions reported?

Thanks!