Coupon events are mandatory. The amount for a broken period depends on the day-count fraction: Act/360 on US corporates, Act/365 on UK corporates, 30/360 on eurobonds, and Act/Act on government bonds. The market quotes a clean price (without accrued) and settles a dirty price (clean plus accrued).
Zero-coupon bonds pay no running interest; they are issued at a deep discount and redeem at par. Coupon stripping pulled the same idea onto couponed government paper: US Treasuries from 1982, UK gilts from 1997. The first coupon on a new issue is often long or short of a regular period, so the first payment is not a neat half of the annual rate.
Some older issues still redeem by drawing: a lottery picks which bonds are repaid early. Those holdings disappear; the rest keep running.
Atlantic Horizon UCITS ICAV holds a US industrial 5% Act/360 for the worked accrued, and a Thames Industrial plc sterling 5% Act/365 for the UK corporate. The Cayman sleeve of the same house holds a Nippon Industrials KK yen eurobond on 30/360. Same coupon idea, three fractions, three dirty invoices. State Street will settle what the local market invoices. Dublin has to accrue what the fraction actually is, not a house 30/360 pasted onto every ISIN.
Buy clean, pay dirty. A dealer who books the clean quote as the settlement amount has underpaid the seller by the accrued. Coupon claims after a fail are the same number, owed to whoever was entitled on record. For the ICAV that claim is a NAV asset; it is not a reason to wait on dealing.
The Irish administrator cannot outsource the accrual. Final NAV stays in Dublin, and the ICAV’s shareholder register stays in Dublin. Custody confirms the coupon credit when the paying agent pays. Accrued interest between coupons is still the fund’s, every dealing day, whether the US line, the Thames Industrial sterling, or the Nippon Industrials eurobond is the one that moved.
A long first coupon, a strip, or a drawing does not change the mandate. They change the fraction, the instrument, or the outstanding nominal. Booking any of them as a “skipped coupon” is how a receivable dies on the books while the market is still paying someone else.