I would follow the investment order:
https://forum.mrmoneymustache.com/investor-alley/investment-order/WHAT
0. Establish an emergency fund to your satisfaction
1. Contribute to your 401k up to any company match
2. Pay off any debts with interest rates ~5% or more above the current 10-year Treasury note yield.
3. Max Health Savings Account (HSA) if eligible.
4. Max Traditional IRA or Roth (or backdoor Roth) based on income level
5. Max 401k (if
- 401k fees are lower than available in an IRA, or
- you need the 401k deduction to be eligible for (and desire) a tIRA deduction, or
- your earn too much for an IRA deduction and prefer traditional to Roth, then
swap #4 and #5)
6. Fund a mega backdoor Roth if applicable.
7. Pay off any debts with interest rates ~3% or more above the current 10-year Treasury note yield.
8. Invest in a taxable account and/or fund a 529 with any extra.
WHY
0. Give yourself at least enough buffer to avoid worries about bouncing checks
1. Company match rates are likely the highest percent return you can get on your money
2. When the guaranteed return is this high, take it.
3. HSA funds are totally tax free when used for medical expenses, making the HSA better than either traditional or Roth IRAs for that purpose.
At worst, the HSA behaves much the same as a tIRA after age 65.
4. Rule of thumb: traditional if current federal marginal rate is 22% or higher; Roth if 10% or lower, or if MAGI is too high to deduct a traditional IRA; flip a coin otherwise.
For those willing to expend a little more energy than it takes to flip a coin, consider comparing current marginal tax saving rate vs. predicted marginal withdrawal tax rate.
If current > predicted, use traditional. Otherwise use Roth.
See Credits can make Traditional better than Roth for lower incomes and other posts in that thread about some exceptions to the rule.
See Traditional versus Roth - Bogleheads for even more details and exceptions.
The 'Calculations' tab in the Case Study Spreadsheet (CSS) can show marginal rates for savings or withdrawals*.
Remember to include all income-dependent effects in your marginal tax rate.
The CSS does include most federal and state brackets, credits (Child Tax, Education, ACA, Earned Income, etc.), phase-ins, phase-outs, and IRMAA tiers.
It may not include some state tax details, FAFSA Expected Family Contribution, and other items irrelevant to most but important to some.
5. See #4 for choice of traditional or Roth for 401k. In a 401k there are no income-based limits for deductions or contributions.
6. Applicability depends on the rules for the specific 401k. See Mega Backdoor Roth IRA.
7. Again, take the risk-free return if high enough. Note that embedded in "high enough" is the assumption that your alternative is "all stocks" or a "fund of funds"
(e.g., target retirement date) that provides a blend of stock and bond returns. If you wish to consider separate bond funds, compare the yield on a fund
with a duration similar to the time remaining on the loan, and put your money toward the one with the higher after-tax interest/yield.
8. Because taxable earnings will still help your FI journey. If your own retirement is in good shape, and you choose to provide significant help for children's college costs,
a 529 plan may be appropriate. Similar to "put on your own oxygen mask before assisting others," do consider funding your own retirement before funding 529 plans for children's college costs.
edit:
in your case, I would start with getting an emergency fund in place, then afterwards begin putting your cash into a roth IRA. After you graduate, if your rate is sub 4%, I think it makes most mathematical sense to pay the minimums and anything left over I would invest. This is what DH and I did (only pay minimums) and we are very happy we did that. We had our SLs around a lot longer and only paid them off a few months ago, but I look at my 401k and brokerage account today and am definitely not upset we prioritized saving.
