Uchi-daka (real value of the yield) (内高)
Uchi-daka (real value of the yield) means kokudaka (crop yield) that was used as the appraisal standard to impose nengu (land tax) to the people of shoryo (territory) of daimyo (Japanese feudal lord) and hatamoto (bannermen) in the Edo period. It is a term opposed to omote-daka, which is the face value of kokudaka assessed by seii taishogun (literally, "great general who subdues the barbarians"), and is also called jitsu-daka.
Detailed Explanation
Omote-daka was calculated based on the land survey officially recognized by the Edo bakufu; however, in many domains the actual uchi-daka was higher than omote-daka and also increasing, thanks to the progress of development of new field in 17th century, the land survey within domains that was based on the increased productivity by innovation of agricultural technique (farming equipments, fertilizer), and tax reform by monopolization of indigenous products.
Generally, for many taihan (large scale domain) of tozama (outside feudal lord) that experienced few relocation throughout the Edo period and which shoryo was not distributed, omote-daka was still the same amount as calculated by Taiko kenchi (Hideyoshi Toyotomi's nationwide land survey) or land survey in the early Edo period, despite that large scale of development of new field had been conducted, and as a result, some areas like Ou, where originally was underdeveloped area, there was a big difference between omote-daka and uchi-daka, for example, the Sendai Domain's omote-daka was 620 thousands koku crop yield while its uchi-daka was one million koku.
In fact, although bakufu (Japanese feudal government headed by a shogun) investigated uchi-daka and they kept the track of it to some degree, omote-daka was still used as the standards for calculating kakaku (family status) and military service that would determine compulsory expenditure of daimyo (Japanese feudal lord) or hatamoto. For this reason, the more uchi-daka becomes higher than omote-daka, the less daimyo or hatamoto will need to pay for military service, compared to their actual income, and therefore they will become more wealthy.
However, if uchi-daka was increased as a result of land survey by the domain, it meant that nengu will be increased in accordance with the productivity - although it was previously collected at comparatively low rate for the actual productivity - and the load of the people of the domain will also be increased. Especially for tozama clans that experienced a large diminishing of the territory had been conducting strict land survey to calculate uchi-daka in order to increase their income and maintain the vassals. It is said that tozama clans tried to set the grade of their land as high as possible, and for example, the Choshu Domain of the Mori clan's uchi-daka was about 750 thousands koku compared to 360 thousands koku. Sometimes uchi-daka registered in the land survey list was higher than the actual productivity of the land, and nengu was calculated based on that uchi-daka, which resulted in harsh tax collection. In the Satsuma Domain of the Shimazu clan, tax was collected based on the land survey list that even included the land not suitable for rice fields and vegetable fields.
In the Edo period, daimyo (excluding taihan of tozama) often experienced transfers of the territories, and although omote-daka was supposed to be the same, transfer could be a promotion to the double amount of uchi-daka or a demotion to the half amount (for example, the Naito clan was demoted from the Iwakitaira Domain to the Nobeoka Domain of Hyuga Province). In addition, in some cases if the promotion/increase was made under the patronage of the shogun, the officially published omote-daka was intentionally kept low (for example, the Makino clan was promoted from the Yoita Domain of Echigo clan to the Komoro Domain in Shinano Province).
Thus, it was impossible to estimate financial affairs of domains by omote-daka, and uchi-daka was the important factor. It can be said that in order to understand the actual power of domains, comprehensive judgment is required based on whether there are good ports or mines, the distance of Sankinkotai (a system under which feudal lords in the Edo period were required to spend every other year in residence in Edo), tax collection according to the development of commerce, and so on.