In Iowa, can I make a change to a will by writing it out and sign and date it

If the change is not a substantial one, then you can execute a "codicil". This is merely an amendment to your exisiting Will. However, in order for it to be legal it the same procedures for creating a Will also apply to creating a codicil. This means that a codicil must be made in writing, signed by the testator (you), or someone in the testator's presence at the direction of the testator, and the testator must declare the will/codicil to be their own. Then 2 witnesses must be in the testator's presence when they signs the codicil, after which the witnesses must also sign the codicil. You are permited to amend your own Will so long as you follow the above procedures. While a lawyer is not required, you may want to have one review any changes that you want to make. A codicil is unlikely to seamlessly fit with an original Will. For example, is it a pure addition or does it negate something in the original document; if it’s supposed to replace part of the first Will, which part? Further, in this day and age of computers, drafting a new Will is not that complicated. In other words, making a new Will is often as easy as making a codicil, so you may just want to purchase an on-line form and execute a new Will. In fact, if the change that you want to make is major, then you should re-do your Will.