Yes, the method and the rate of depreciation can be changed but only in the following circumstances.
(i) The change is to comply with statutory regulations. or
(ii) The change would help in better understanding of the true financial position of the business. Also, the change and its effect on profit should be disclosed in the financial statements of the enterprise.

The concept of going concern assumes that a business firm would continue to carry out its operations indefinitely. Due to this concept distinction is made between capital and revenue expenditure and thus, assets and liabilities are recognised.

(i) Accounting concepts are the basic assumptions or conditions upon which accounting has been laid.
(ii) Accounting concepts are the results of broad consensus.
(iii) The word concept means a notion or abstraction which is generally accepted.
(iv) Accounting concepts provide unifying structure to the accounting process and accounting reports.

The main features of book-keeping are:
1. It is the process of recording transactions in the books of accounts.
2. Monetary transactions only are recorded in the accounts.
3. Book-keeping is the primary stage in the accounting process.
4. Book-keeping includes journalising and ledger processing.

(i) Accounting Standards provide the framework and norms so that the financial statements of different enterprises become comparable.
(ii) It becomes necessary to standardise the accounting principles and policies to ensure consistency, comparability, adequacy and reliability of financial reporting.
(iii) Accounting standards in India are issued by the Institute of Chartered Accountants of India (lCAI).
Definition:
In the words of Kohler, "Accounting standards are codes of conduct imposed by customs, law or professional bodies for the benefit of public accountants and accountants generally".

(i) "Business units last indefinitely". This statement is used in Going Concern Concept.
(ii) Going concern concept influences Accounting practices in relation to valuation of assets and liabilities, depreciation of the fixed assets, treatment of outstanding and prepaid expenses and Incomes.
(iii) The values involved in the going concern concept are
1. Growth: By following the going concern concept, business activities are to be carried out for future growth. 
2. Preparing for future: By following the going concern assumption, business firm always intends to prepare for the future.

(i) Only financial transactions are to be recorded because it is due to Money Measurement concept, which states that only those transactions are to be recorded in the books of accounts which consist of cash.
(ii) Hence it is concerned with the Nominal value not the real value.
(iii) For example Mohan purchase television for Rs.12,000. So this, will recorded in journal entry book as it has cash transactions.

(i) According to this concept, revenues during an accounting period are matched with expenses incurred during that period to earn the revenue during that period.
(ii) This concept is based on accrual concept and periodicity concept.
(iii) Periodicity concept fixes the time frame for measuring performance and determining financial status.
(iv) All expenses paid during the period are not considered, but only the expenses related to the accounting period are considered.

(i) Accounting Conventions:
1. The word convention refers to traditions or customs. The accounting convention describes the customs or traditions followed as a guide to the preparation of accounting statements.
2. Modern business world has accepted the utility of these Accounting conventions in making financial statements more realistic, reliable, and useful to all concerned parties. The following four conventions are generally adopted over a period of time.
(ii) Convention of consistency:
1. The consistency convention implies that the Accounting practice should remain the same from one year to another. The results of different years will be comparable only when same accounting methods are followed from year to year.
2. For Example: If a firm follows the original or fixed installment method of charging depreciation since its purchase/construction, the method should be followed without any change.
(iii) Convention of full disclosure:
1. The accounts must disclose all material information. The Accounting reports should disclose full and fair information to the related parties. The financial position and performance should be disclosed very honestly to all the users.
2. All the information should be relevant, reliable, comparable and understood by all the concerned authorities.
(iv) Convention of conservatism or prudence:
It is a policy of caution or playing safe. While recording the business transactions one has to anticipate no income but provide for all possible losses.

(i) Accounting principles are the rules of action or conduct which are adopted by the accountants universally. Such accounting principles are known as Generally Accepted Accounting Principles (GAAP).
(ii) Accounting concepts are bye-laws whereas conventions are guidelines based upon customs or usage. The important Accounting concepts are listed out below :
1. Business entity concept:
a) This concept implies that a business unit is separate and distinct from the persons who supply capital to it.
b) Based on this concept, accounts are prepared from the point of view of the business and not from the owner's point of view. Hence, the capital contributed by the owner is treated as a liability of the business.
c) This concept helps in keeping business affairs free from the influence of personal affairs of the owner.
2. Money measurement concept:
a) This concept implies that in Accounting, every transaction, or happening or event is recorded in terms of money.
b) In other words, only those transactions, which can be expressed in terms of money, are recorded in the accounts.
3. Going concern concept:
a) It is the basic assumption that b.usiness will continue for a quite long time and it will go on and will not be closed down or stopped for quite a long time.
b) Going concern concept influences Accounting practices in relation to valuation of assets and liabilities, depreciation of the fixed assets, treatment of outstanding and prepaid expenses and incomes.
4) Cost concept:
a) As asset is recorded in the books at the value of price paid for it at the time of its purchase and the cost paid will be the base for all further Accounting.
b) It is recorded at cost at the time of its purchase, but is systematically reduced in its value by charging depreciation.
5) Accounting period concept:
a) The true profit or loss earned by a business unit can be ascertained only when the business is liquidated.
b) But many persons such as proprietors, investors, creditors, employees and the government are interested in knowing the performance of the business unit.

Meaning of Book-keeping:
(i) Book-keeping is the process of recording financial transactions in the books of accounts.
(ii) It is the primary stage in the accounting process.
(iii) It includes recording the transactions and classifying the same under proper heads.
(iv) Book-keeping work is of routine nature.
Features of Book-Keeping :
Following are the features of book-keeping :
(i) It is the process of recording transactions in the books of accounts.
(ii) Monetary transactions only are recorded in the accounts.
(iii) Book-keeping is the primary stage in the accounting process.
(iv) Book-keeping includes journalising and ledger processing.