3% corporate tax for small companies. Small companies must have a share capital under 50,000 OMR, income under 100,000 OMR, fewer than 15 employees, and not be a utility, transport, or financial services company. For a small business, it's quite easy to qualify. Otherwise, the corporate tax is 15%.
No personal income tax.
There are a couple of residence by investment paths but they are not nearly as popular or well established as UAE. IIRC, you need at least a few︀ hundred thousand OMR or equivalent to qualify.