Contribution priority for retirement accounts

It’s a common sense to pay off the debt with the highest interest first. This also applies to retirement investment accounts.

For residents in the US, priorities are in this order:

1. Company-matched 401k account.
2. ROTH IRA account.
3. Non-matched 401k and traditional IRA account.
4. Taxable account.

Company-matched account is first because every dollar contributed is matched by your employer. This is an automatic 100% return on investment. The next dollars should go to a ROTH IRA account rather than non-matched 401k or traditional IRA account. The reason is that, at retirement age, withdrawal from ROTH IRA account is tax-free while the 401k and traditional IRA are taxed, i.e. guaranteed loss. The last dollar shall go to the catch-all bucket, a taxable account.