As far as I am aware, Scottish armies were never paid during the medieval period. The Scottish crown seems to have lacked the administrative complexity and centralized authority to raise paid armies on a large scale. While this is a given during the Scottish Wars of Independence, when the authority and person of the Crown was often in doubt, it seems to have continued to be the case into he Early Modern period. As an examples The army raised for the Flodden campaign in 1513 was an all volunteer force and did not receive wages. The king of Scots typically did not have anything like the legal authority or administrative control over his kingdom that the King of England enjoyed. Regions like the Isles and Highlands reminded resistant to royal authority for a very long time, remaining a serious thorn in the side of Scottish kings well into the early modern period.

By contrast, this was the exact period in which paid service was becoming the norm for English armies. The increased military demands of Edward I’s wars, notably his conquest of wales, and the failure of the feudal array which accompanied them necessitated that the king find a new way to raise armies. While paid military service had existed in England since the Norman conquest (or before) it had always been on a limited scale and supplemental to more tradition feudal means of raising armies. Edward I (Longshanks) I was the first English king to institute paid military service on a wide scale. During his reign service in exchange for wages became the standard form of military service in England, although it remained controversial and continued to exist alongside more traditional forms of feudal military service. For most of Edward I’d reign the magnates (the traditional feudal military elite) remained openly hostile to the idea of paid military service. They argued that it infringed upon their traditional privileges and resented the way that paid service would tie them and their men more directly to royal authority (in fairness to them, they were absolutely right in both accountsr).

During Edward I’d reign, the actual infrastructure of paid service was not yet fully refined. We begin to see the famous contracts of indenture emerge during his reign, but they are rough and not yet refined for royal use. As a result they are generally limited to private contracts between magnates and lesser members of the aristocracy. Additionally, traditional feudal service had not yet disappeared from the military scene and the lines between gratuitous feudal service and paid wage service were often blurred. wage service often flowed directly from feudal service. It was not unknown for parts of a retinue to be serving for wages while other parts were fulfilling feudal obligations (either to their lord or to the king). Similarly, many men would only begin drawing the kings wages after fulfilling their feudal obligations. To further complicate matters, some men would serve for free due to their proximity to the conflict or in pursuit of pardons for their crimes.

By the time of Edward III magnate opposition to wage service had largely disappeared and almost every member of a given English army would be receiving wages from the crown. It was during Edward III’s reign that the now famous contracts of indenture become truly widespread. In effect, a given captain (unlike in earlier periods, these captains were not always of high social rank although they usually were) would enter into a formal contract with the king for a given number of certain type or types of solider for a given period of time at a fixed wage rate. Captains would then form contracts with individual men, or commonly with sub contractors to meet their manpower commitments. The wage rate was fixed by the crown, but It was possible for a captain to contract with his soldiers for a lower wage rate. In such cases the captain could pocket the difference, making a tidy profit.

Throughout the period soldiers wages would be determined by their equipment, method of service and social rank. Knights received higher wages than equivalently equipped but unknighted men at arms (such men were generally called sergeants under Edward I and esquires under Edward III but the terms were not standardized and remained interchangeable throughout the period). By contrast, a mounted horsemen who lacked barding (horse armor) for his warhorse, sometimes called a hobilar, was paid at a significantly lower rate than an unknighted man at arms. Under Edward III mounted men with unbarded warhorses drew the same pay as mounted archers (interesting side note, Andrew Ayton had argued that many of the archers listed in 14th century lay roles may actually have been cavalrymen with unbarded horses and not archers at all).

The wage rate was typically by the day and wages were paid to the retinue leader (I believe up front) who was responsible for paying them out to his men. I do not know if the method or time table for payments was ever standardized but I believe that they were paid out monthly. Generally men were considered “under the kings pay” only after they had arrived at the muster point, passed inspection and had their horses assessed by the constable (on some occasions they do appear to have received back pay for the period in which they were traveling to the muster point). This system was fairly well standardized by the reign of Edward III, but it remained rather messy during Edward I’s reign.

As far as the the arrayed infantry levies are concerned, royal pay usually began after they had passed the borders of their home shire, prior to that they may have received wages from their local community. English medieval levies were paid during this period and while the method of their recruitment varied, they do not seem to have usually been conscripts.

While the financial systems and practices that underpinned English military society were largely (though not completely, various experiments were attempted) standardized by the time for Edward III, under Edward I It is important to note that there was no fixed system. Specific practices could vary considerably from campaign to campaign or from year to year, especially in the case of the levied infantry. Both Edward I and Edward II attempted to alter the system of militia service in England, some attempts more successful than others.

What is important to remember about wages in this period is that they don’t seem to have been conceived as a form of income, in the sense that people did not enter military service expecting to make money from their wages. Wages seem to have been a way to cover a soldiers daily expense and alleviate the considerable financial burden that accompanied military service. War was expensive for all parties involved and it was the relative expense of serving in the king’s army (both in terms of daily costs and potentially disastrous financial misfortune such as ransoms or the death of a warhorse) that created a great deal of the friction between the king and the military class. By introducing wages Edward I was able to off set a great deal of the expenses associated with service and by extension, make it more palatable to the military class, as well as open repeat military’s revive to a wider subsection of the English population. However, wages were just a part of what Andrew Ayton has called “a package of benefits” that accompanied military service and that would become more refined as the century progressed. Things like compensation for lost horses, Regqrd payments, ransoms and good old fashioned loot remained important incentives for service.

I hope this helps!