The new formula for calculating child support maintenance came into force on 3 March 2003. There are transitional arrangements to bring existing cases into the new system, and some cases will be integrated sooner than others. However, for most cases the effect of the changes will be that, where there is an existing maintenance assessment, it will continue to be effective under the old system for the time being whereas cases where the liability arises for the first time on or after 3 March 2003 will be dealt with under the new system. The effect of this for the practitioner is, therefore, that the two systems will continue to run in tandem for some while and knowledge of both systems will have to be maintained. A point of practical importance is that, as the old formula depends on the social security rates for the time being, calculations under the old system have to be updated every year. The Child Support Calculation Kit 2004/2005 contains: A calculation pack under the old system using updated figures as at 6 April 2004; A calculation pack using the new formula for cases where the liability first arises on or after 3 March 2003; A CD-ROM which includes easy-to-use spreadsheets to carry out the above calculations under either the old or new formula. You simply enter the information required and calculations are performed instantaneously; A bulletin examining both the benefits and detriments of the new system, and the impact of the child support upon a client's state benefits. The Child Support Calculation Kit 2004/2005 will provide the practitioner with the assistance that is needed during this transitional period.