People confuse a NIN modification with a NIN slip reissue because both involve NIMC, both are handled through NIMC's online services, and both end with an updated-looking document in your hand. They solve different problems.
Here is the distinction, a quick test for your own situation, and what each one costs, so you do not pay for the wrong service by mistake.
What each service actually changes
A modification changes something on your NIN record itself: your name, date of birth, address, phone number or email. The number stays the same, but the data behind it is different afterwards.
A reissue does not change your record at all. It reprints your slip with whatever details are already on file, which only helps if those details are already correct.
A quick test to tell them apart
Ask yourself one question: is the information on your NIN record wrong, or is it correct but the physical slip is lost, damaged, or hard to read?
Wrong information means a modification. A correct record with a missing or damaged slip means a reissue. If you are not sure which applies, a NIN status check can confirm what is actually on your record before you decide.
What each one costs
NIMC charges ₦600 for a reissue. A modification costs ₦2,000 for most fields, or ₦28,574 specifically for a date of birth correction.
The gap between these figures is a useful check in itself. If you expected to pay the smaller reissue fee and the portal is asking for one of the larger modification fees, you may be in the wrong flow for what you actually need.
What happens if you pick the wrong one
Reissuing a slip that already has wrong information on it just gets you a fresh copy of the same mistake. It does not fix anything, and you pay again to solve the actual problem afterwards.
Applying for a modification when nothing on your record is actually wrong is the opposite error. You pay a higher fee and go through an evidence-gathering process you did not need, for a result that looks identical to what a simple reissue would have given you.
Where to start each request
If your record itself needs to change, start with NIN modification and see what NIN modification covers for how NIMC treats each field.
If your record is correct and only the slip needs replacing, that is a reissue rather than a modification, and sits outside what this article covers in detail. Confirm your record is actually correct first, since assuming so and reissuing anyway is exactly the mistake this comparison is meant to help you avoid.
For more on specific modifications, browse the NIN and NIMC hub.