The financial implications of delays in conception at different stages of lactation in the average and the high yielding dairy cows were investigated. Variables included in the calculations were net loss in annual yield, lost income from a calf, cost of extended dry period, cost of slipping in calving pattern, cost of extra veterinary treatments and AI services, benefit of a delay in calving for reduced risk of production diseases, potential benefit of delay in conception on milk yield from the current lactation, and the value of quota leasing. For the average yielding cow, the net cost of one day of delay in conception was calculated at £2.41 when conception is delayed from 85 to 100 days post-calving, increasing to £5.02 per day if conception occurred at 146 to 175 days post-calving. After taking value of quota leasing into account, the net cost of a lost day was calculated at £1.73 and £3.55 per day for the two delay intervals respectively. For the high yielding cow, the net cost of one day of delay in conception was calculated at £2.48 when conception is delayed from 85 to 115 days post-calving, increasing to £6.52 per day if conception occurred between 206 and 235 days post-calving. The net costs after quota leasing being considered were calculated at £1.68 and £4.08 per day for the two delay intervals respectively. On the basis of the above estimations, and after considering the cost of culling for poor fertility, it was concluded that it is a cost-effective option to keep trying to get the typical average cow in calf until 266 days post-calving, whereas the breakeven point for the high yielding cow is at 290 days post-calving.