The phrase to have one’s work cut out means to be faced with a hard or lengthy task.

This phrase is supposedly a metaphorical allusion to the preparation of fabric to be worked on: once the shapes have been cut out, the tailor still has a lot of sewing to do, by hand in the past, before the cloth becomes a garment.

It must be said however that the phrase has never appeared with explicit reference to tailoring and that this supposed allusion to the preparation of fabric only constitutes the best explanation. One of the meanings of the phrasal verb to cut out is to fashion or shape by cutting out of a piece of cloth, as in the following passage from The rule of reason, conteinyng the arte of logique (London, 1551), by the humanist and administrator Thomas Wilson (circa 1525-1581):

Although one haue a cloth, yet can he not haue the vse of it, excepte the tailer cutte it out.

The original figurative sense of work cut out was neutral: it was merely work to be done. This is first recorded in A discouery of the great subtiltie and wonderful wisedome of the Italians whereby they beare sway ouer the most part of Christendome, and cunninglie behaue themselues to fetch the quintescence out of the peoples purses (London, 1591), by ‘G. B. A. F.’:

There is more doctrine and instruction in one onely Epistle of S. Peter and S. Paul, nay to speake of lesse, in one onely Chapter, the fift to the Galathians, then [= than] the most perfect and holiest men in the world could euer accomplish or fulfill. […] Sée then here is more worke cut out in this one Chapter, then [= than] they and their disciples will euer be able to do.

The phrase to cut out work for a person originally meant to prepare work to be done by a person, so that the passive form to have one’s work cut out by a person meant to have one’s work prepared by a person, as in this passage from Several Sermons Preach’d on the whole eighth chapter of the Epistle to the Romans (London, 1672), by the English clergyman Thomas Jacomb (1622-87):

I resolv’d to fix upon some continued Discourse in Holy Writ, where I might have my work cut out for me by the Spirit of God from time to time, by which being determined I might be freed from self-perplexing and time-wasting distractions.

Gradually, to have one’s work cut out for one and variants came to mean to have as much to do as one can manage, especially in the time available. An early instance of this is found in a letter from Paris, published in Jackson’s Oxford Journal (Oxford, Oxfordshire) of 13^th May 1758, during the Seven Years War (1756-63), which ranged Britain, Prussia and Hanover against Austria, France, Russia, Saxony, Sweden and Spain:

We suppose the Hanoverian Army will not be long idle, as it is already reinforced to above 60,000, and Prince Ferdinand has provided for its Subsistance [sic] during the Campaign; so that we seem to have more Work cut out for us than we can tell how to manage.

An early occurrence of the current form to have one’s work cut out, not followed by a complement and in its current sense, is found in the following from the Morning Advertiser (London) of 13^th March 1822:

BOXERS.—The much talked of Great Match, so long desired by Martin, is at length made between himself and Randal, for the enormous sum of One Thousand Guineas, to take place in September.—Martin has his summer work cut out, as he is matched to fight Ab. Belasco (the best Jew fighter since Mendoza,) on the 7^th of May, for 200 Guineas, and fifty a side is deposited.

 

To cut out work for someone corresponds to the obsolete French expression tailler de la besogne à quelqu’un, recorded for example in the first edition (1694) of the Dictionnaire de l’Académie française (via the Anglo-Norman agent noun taillour, the French verb tailler is the origin of English tailor):

On dit prov. & fig. Tailler de la besogne à quelqu’un, pour dire, Luy susciter bien des affaires, ou luy donner beaucoup de choses à faire.
On dit aussi fig. Donner bien de la besogne à quelqu’un, luy tailler de la besogne, pour dire, Luy donner de la peine, de l’exercice, & de l’embarras &c.
     translation:
One says proverbially and figuratively to cut out work for someone, to mean, to cause him/her many concerns, or to give him/her many things to do.
One also says figuratively to give someone a lot of work, to cut out work for him/her, to mean, to cause him/her trouble, effort, and inconvenience, etc.

The obsolete French expression de la besogne taillée corresponds to work cut out. For example, in Antidote ov contrepoison contre les conseils sangvinaires et enuenimez, de Philippe de Marnix Sʳ de Sᵗᵉ Aldegonde (1597?), Emmery de Lyere wrote:

Entrant en nous mesmes, regardons nous, estudions nous, & n’ayons affaire qu’a nous, controllons nous, & nous y trouuerons de la besoigne taillee pour toutte nostre vie.
     translation:
Entering into ourselves, let’s look at ourselves, let’s study ourselves, and let’s deal only with ourselves, let’s control ourselves, and we will find there work cut out for our whole life.