Tips on minimizing tax exposure

[NextLevelOPM]

Admittedly a broad question, I'll try and narrow it down with specifics:

I started a project management LLC.  I have contracts, and the funds get ETF'd into a business account.  There are really little to know business costs at this time: no employees, no benefits.  No advertising, all previous employers.  Known items to deduct: I have software costs, some computer and printer costs, I use my car from time to time, I use 400sf of my house.    I renovated it, but as I still am W2 and this is a side hussle I heard that I cannot deduct that renovation. 

I'm having a nice pile of income that I would like to spend (future house renovation), and not just give away to the government because my expenses are low.

For tax purposes we will be married filing jointly with 2 W2s, and then filing a Schedule C for the LLC.  It will be one combined tax return.

We have health insurance through W2 employers.  We have 401ks through them as well.  They are not maxed out however.  That being said, how can I start ANOTHER 401k/IRA via the LLC.  And do the values from both get combined etc.   Still, that's only $6k looks like for SEP IRA or Solo 401k - or is it 25% (Big Difference!)  I guess this seems the way to go.

Is this basically it in terms of big "savings"?  What am I missing?  The other ones, in my case, seem like small potatoes ($5k for software and computer equipment, $1k for mileage due to Covid).  Or do I just need to manage my own expectation of how much taxes I'll be paying?       

I have three children, have not started 529 college savings plans.  Heard that is deductible at state level, not at federal.  Not sure how that would work being an LLC/using those funds for this.

[NextLevelOPM]

FYI, this is turning into interesting reading RE: solo 401ks.  Basically can shield up to $58k? :https://ttlc.intuit.com/community/retirement/discussion/solo-401k-with-a-solo-roth-401k-and-mega-bac... 

[AHelper]

Hello NextLevelOPM,

No matter how long people have been self-employed I suggest taking a peak at the IRS Small Business and Self-Employed section for tips and tricks to hang on to their hard earned money. 

Small Business and Self-Employed Tax Center 

One can also assume that you would be paying yourself reasonable compensation as a member manager (or however you set up your LLC) There are ways to utilize that to most efficiently spend the income received into the business account.

Managing your expectations as well as potential for quarterly taxes can certainly help prevent sticker shock if and when a tax amount is due.  The TurboTax TaxCaster can give you a pretty good idea of what to expect.

529 accounts are very good to help with state tax liability as well. 

The article you found on Solo 401k's is a good one especially as it reminds you of overall annual limits. Your best bet at this time would be to play with the TaxCaster and maybe talk to a payroll company to see what is needed to get you set up on that end.