AAT Principles of Costing Update

In this blog, Ali Ryder, our AAT Production Manager, explains the upcoming changes to the PCTN assessment.

AAT Principles of Costing | First Intuition

AAT Principles of Costing Update

In this blog, Ali Ryder, our AAT Production Manager, explains the upcoming changes to the PCTN assessment.

From Monday 15th April 2024, the AAT Principles of Costing assessment will only accept spreadsheet formulas in certain stipulated formats. This is to enable the assessment to be fully computer-marked. It is important to understand that just because something works in Excel, doesn’t mean it will be marked correct in your assessment!

The guidance, which can be accessed via the references panel in the assessment, is as follows:

You should:

  • Manually enter cell references to relevant figures in the table.
  • Use standard round brackets ( ) where relevant.

You should not:

  • Use directly entered numbers in place of cell references.
  • Use PRODUCT in formulas for multiplication.
  • Use individual cell references (e.g. B1+B2+B3) within SUM functions.
  • Include unnecessary positive/negative signs to modify a calculation.
  • Include unnecessary spaces or commas.
  • Include unnecessary zeroes within cell references, e.g. A01 instead of A1.
  • Include additional cell references not relevant to the calculation.

Let’s explore this in more detail by thinking about the types of formula you may need to use.



If you need to add up a list of cells, it would be acceptable to use the + key, for example =A1+B1+C1.

It would also be acceptable to use the SUM function, for example =SUM(A1:C1).

However, it would not be acceptable to combine the two. For example, =SUM(A1+B1+C1) would not be acceptable, because =SUM is unnecessary in this formula.

Similarly, you should not use commas in a SUM formula. For example, =SUM(A1,B1,C1) would not be acceptable.

Note: Only addition calculations should begin with =SUM. You should not use the Sum function for subtraction, multiplication or division.


You need to avoid using unnecessary positives or negatives to begin or modify your formulas.

Rearrange your calculation to find the simplest way of expressing it. For example, =C1-B1 would be acceptable, but =+C1-B1 and =-(B1-C1) would not be acceptable, because these are unnecessarily long-winded.


The assessment will accept the cells being entered in different orders. For example, =A1*B1 and =B1*A1 would both be correct.

There is a function in Excel called =PRODUCT which multiplies all the referenced cells together. You should not use this in any of your formulas.


We often use division when we are calculating one number as a percentage of another. If you are calculating a percentage, you need to remember to multiply it by 100. For example, to calculate C1 as a percentage of A1, you would need to enter =C1/A1*100.

This differs from Excel, where you do not need to multiply by 100, so be careful! You should always sense-check the answers to your formulas.

General Guidance

Your formulas will be marked wrong if they include:

  • unnecessary spaces
  • commas
  • square brackets [ ] or curly brackets { } – you must use ( )
  • numbers in place of cell references – e.g. =A1*50
  • redundant references to cells not required for the calculation
  • adding 0s to cell references – e.g. A01, rather than A1

Sometimes you will be asked NOT to use a formula in a particular cell. In this case, work out the answer on your calculator and type the number in.

On the AAT Lifelong Learning Portal, you will find a “Spreadsheet simulation familiarisation resource” and the practice assessments for this unit. It is essential that you use these to familiarise yourself with the functionality of the spreadsheet simulation question type. Remember, it does not behave exactly like a spreadsheet so you need to be comfortable with how it works before you sit your assessment!

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