FUNDCOMP needs to be determined for each year of instance. The 18-month long course therefore needs to be broken into two years of instance, the first being 12 months long (January to December) and the second being six months long (January to June).
In the first ILR, the student will only be part way through their year of instance and so FUNDCOMP=3 would be returned unless they had already failed to complete by the point the ILR was submitted.
In the second ILR return, the student will have completed their second year of instance and so FUNDCOMP = 1 or 2 should be returned as appropriate for the second year of instance.