Aiming as high as possible sounds like sensible advice until you try to plan around it. What actually matters when you are deciding how long to study is the level at which work starts happening in Korean. Fix the target level first and your study timeline and application timing follow from it.
What each level signals to a hiring manager
TOPIK is administered in a beginner section and a combined intermediate-advanced section, and results are graded from level 1 to level 6. In recruitment those numbers are read roughly as follows. Level 3 and below suggests you can order food and ask directions but will struggle with work documents and meetings. Level 4 is read as everyday conversation plus straightforward workplace communication. Levels 5 and 6 indicate you can handle specialist terminology and write reports in Korean.
The requirement varies more than people expect
Foreign-invested companies and some technology firms operating in English may not ask for TOPIK at all. Most Korean companies, however, run reporting, meetings and documentation in Korean, and hire accordingly. Public institutions and state-owned enterprises are the strictest end of the range, where level 5 or above often functions as a requirement rather than a preference. Work out which category your target employers fall into before setting your goal, because preparing for level 5 when level 4 would have been accepted costs months.
It also counts toward residence status
Korean language ability is scored in the assessment for some work-related residence statuses. A given level does not guarantee approval on its own, but it is the kind of item that separates otherwise similar applications. How it applies to your specific status is worth confirming through HiKorea or the 1345 immigration contact centre rather than assuming the general case fits you.
Watch the expiry date
TOPIK results are valid for two years from the date they are announced. Job searches stretch, and applicants regularly discover that the score they worked for has expired at the moment they need it. Check the validity window before submitting documents, and since the test runs several times a year, book a sitting before expiry rather than after. Registration periods and test dates are published by the administering institute.
Study approaches by level and section-by-section preparation are in the TOPIK and employment guide on the WeBring blog.