Offered IHR today

[flaminmoses]

any carried forward from previous year you would get.
then any accrued from april 1st till your leave date minus any you had taken.

so if youd worked a week into april youd only get a few hours for that year presuming you hadnt taken that week off

[fishtank]

I was told that IHR was calculated by time served, time to do, + 9 weeks pay in lieu of notice + holiday entitlement, only the holiday pay would be taxed, the average is 34weeks pay + 9 weeks in lieu+ holiday, which is about a years pay

IHR with lump sum is a flat rate 34 weeks pay plus PILON plus annual leave.
The only service requirement is that you have completed 12 months.
After that,length of service is meaningless other than in calculating PILON which is...

1-9 years...9 weeks.
10 years...10 weeks.
11 years...11 weeks.
12+ years...12 weeks.