Asset Life Extension for STL - Asset life in decimal

My client would like to apply an extended life to assets with the following rules:

Asset Cost = 10000     Placed in service 01/01/2013 and monthly depreciated.

Life = 10 years

Depreciate method = STL (Straight Line)

In August 2017, the client decide to extend the life of asset to 15 years and to apply this extension from the beginning of the year i.e. 01/01/2017.

       Years                 Deprec.         NBV           Years   Deprec NBV
                                 Expen.                                                Expen.       

2013 Year 1   1000       9000           Year 1       667   9333   

2014 Year 2   1000       8000           Year 2       667   8666   

2015 Year 3   1000       7000           Year 3       667   7999   

2016 Year 4   1000       6000           Year 4       667   7332   

2017 Year 5   1000       5000           Year 5       667   6665   

    Year 6   1000       4000           Year 6       667   5998   

    Year 7   1000       3000           Year 7       667   5331   

    Year 8   1000       2000           Year 8       667   4664   

    Year 9   1000       1000           Year 9       667   3997

     Year 10 1000           0           Year 10      667   3330   

                                    Year 11      667   2663   

                                    Year 12      667   1996   

                                    Year 13      667   1329   

                                    Year 14      667    662   

                                     Year 15      667     -5

The life extension is applied on the Net Book Value at the end of year 4 = 6000.